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N5Lesson notes · Oct 8, 2026

Heavy in Japanese: how do you say 重おもい (omoi) and its opposite 軽かるい?

"Heavy" in Japanese is 重おもい (おもい, omoi), and its opposite is 軽かるい (かるい, karui) — both are i-adjectives, and both stretch far beyond physical weight into moods, conversations, responsibilities, and even personalities.

If you search "heavy in Japanese hiragana" or "heavy in Japanese kanji," the short answer is: おもい in hiragana, 重おもい in kanji. The long answer is more interesting, because 重おもい shows up in places English "heavy" never goes, and it shares its sound with a completely different word that learners mix up all the time.

The basics

How do you write and say "heavy" in Japanese?

The word is 重おもい, read おもい. The kanji 重じゅう carries the idea of weight and importance, and the い on the end marks it as an i-adjective. You can write it in hiragana (おもい) when you are not sure of the kanji, but adults and most textbooks use 重おもい.

このかばんは重おもいです。 — This bag is heavy. (polite, everyday) 荷物にもつが重おもいね。 — The luggage is heavy, huh. (casual, said to a friend)

The opposite is 軽かるい (かるい): light in weight, not heavy.

この箱はこは軽かるいです。 — This box is light. (polite) 軽かるいから、一人ひとりで持もてるよ。 — It's light, so I can carry it by myself. (casual)

How do you conjugate 重おもい and 軽かるい?

Both follow the regular i-adjective pattern, so everything you learn for one works for the other. If you want the full rulebook for this adjective type, see i-adjectives vs na-adjectives.

Meaning 重おもい (heavy) 軽かるい (light)
Plain present 重おもい 軽かるい
Polite present 重おもいです 軽かるいです
Negative 重おもくない 軽かるくない
Polite negative 重おもくないです 軽かるくないです
Past 重おもかった 軽かるかった
Past negative 重おもくなかった 軽かるくなかった
Connecting (and) 重おもくて 軽かるくて
Before a noun 重おもい荷物にもつ 軽かるい荷物にもつ

The i drops and gets replaced: 重おもい becomes 重じゅうくない, 重じゅうかった, 重じゅうくて. The one irregular adjective, いい, is not involved here, so this one is easy.

昨日きのうの荷物にもつは重おもかったです。 — Yesterday's luggage was heavy. (polite, past) 思おもったより重おもくなかった。 — It wasn't as heavy as I thought. (casual, past negative) このリュックは重おもくて、大変たいへんだった。 — This backpack was heavy, so it was hard. (casual, connecting with て)

Do you put の between 重おもい and the noun?

No. This is the single most common error with this word. An i-adjective attaches straight to the noun with nothing in between.

重おもい荷物にもつ — heavy luggage (correct) 重おもいの荷物にもつ — (wrong — no の needed)

The の belongs to nouns ("my bag" is 私わたしのかばん), and na-adjectives take な. I-adjectives take nothing at all. You will see 重おもいの used in one real situation: when the adjective is standing in for the noun, as in 重おもいのはこっち, "the heavy one is this one."

Beyond the basics

Why does 重おもい describe things that are not physical?

Japanese uses 重おもい for anything that feels like a weight pressing on you. Many of these expressions are common enough that you will meet them in your first year of study.

Expression Meaning Feel
話はなしが重おもい The conversation is heavy Serious, hard to carry emotionally
気きが重おもい I feel heavy-hearted Dreading something
責任せきにんが重おもい The responsibility is heavy Formal, serious
頭あたまが重おもい My head feels heavy A mild headache or fog
体からだが重おもい My body feels heavy Tired, sluggish
重おもい病気びょうき A serious illness Medical, formal

今日きょうは朝あさから気きが重おもい。 — I've felt heavy-hearted since this morning. (casual, dreading something) ちょっと話はなしが重おもいから、また今度こんどね。 — That's a bit of a heavy topic, so let's do it another time. (casual, softening) 風邪かぜをひいて、体からだが重おもいです。 — I caught a cold and my body feels heavy. (polite) これは責任せきにんが重おもい仕事しごとです。 — This is a job with heavy responsibility. (polite)

Notice the pattern: the thing that feels heavy is the subject, marked with が (話はなしが重おもい, not 話はなしは重おもい as a default). The person feeling it is usually left out and understood from context.

What does it mean when someone calls a person "重おもい"?

In relationships, 重おもい describes someone whose feelings or expectations feel like too much to carry. Typically it is about love: messaging constantly, expecting a lot, or taking things very seriously very fast.

あの人ひとの愛あいは、ちょっと重おもい。 — That person's love is a bit much. (casual, said about someone's feelings)

Be careful with this one. Calling a real person "重おもい人ひと" to their face is harsh, because you are telling them they are a burden. You will hear it far more often about a third party in a casual conversation, or in an anime where a character's devotion is played as intense. For the romantic side of this, see kataomoi vs ryouomoi, which covers the "one-sided" and "mutual" kinds of love that this adjective often gets attached to.

How does 軽かるい work as a figure of speech?

軽かるい is not only the physical opposite. It also means "casual," "easy," or "not serious" — and sometimes "not thoughtful," which is where it turns negative.

Expression Meaning Feel
軽かるい食事しょくじ A light meal Positive or neutral
軽かるい運動うんどう Light exercise Positive or neutral
軽かるいけが A minor injury Neutral
口くちが軽かるい Loose-lipped, can't keep a secret Negative
軽かるい人ひと A flighty, casual person Often negative

お昼ひるは軽かるいものでいいです。 — Something light is fine for lunch. (polite) あの人ひとは口くちが軽かるいから、秘密ひみつは言いわないほうがいいよ。 — That person can't keep a secret, so it's better not to tell them anything. (casual, warning)

There is also a set of "light" body-part idioms, such as 腰こしが軽かるい (quick to get up and help). Some others in the same family refer to a person being too casual about intimacy, and they are rude. As a learner, you do not need to use them. It is enough to know that "軽かるい + body part" can describe someone's character, and to ask a teacher or a native friend before you use one.

Is "light" in 軽かるい the same word as the light in 光ひかり?

No. They only share the English word. 軽かるい (かるい) is about weight and seriousness. 光ひかり (ひかり) is the light you see. If you are looking for "light" in the sense of brightness or a lamp, that is a different article: bright in Japanese: akarui. The English word "light" covers two ideas that Japanese keeps firmly apart, so choose the Japanese word by the meaning, not by the English spelling.

What is 重おもたい, and how is it different from 重おもい?

重おもたい (おもたい) means the same thing as 重おもい, with a slightly softer, more spoken feel. It often sounds like a complaint or a feeling rather than a measurement.

この本ほん、重おもたいなあ。 — This book is heavy, ugh. (casual, a little grumbling)

You can use either one in daily speech. If you need to choose, 重おもい is the safe one for writing and for polite speech.

How do you ask about weight?

To ask how heavy something is, you can use the noun form 重おもさ (おもさ): "the weight."

この荷物にもつの重おもさは、どのくらいですか。 — How heavy is this luggage? (polite, "about how much") これ、何なにキロですか。 — How many kilos is this? (polite, direct) 何なにキロくらいありますか。 — About how many kilos is it? (polite, softer)

When you want a plain "How heavy is it?" without a number in mind, どのくらい重おもいですか works too. The answer is usually a number plus キロ.

だいたい五ごキロです。 — It's about five kilos. (polite)

The more formal written word is 重量じゅうりょう (じゅうりょう), "weight" as a measured quantity. You will see it on shipping forms, airline luggage rules, and product pages, but you will rarely say it out loud.

荷物にもつの重量じゅうりょうは二十にじゅうキロまでです。 — The luggage weight limit is up to twenty kilos. (polite, official wording)

Rule of thumb: speak with 重おもさ or 何なにキロ, read and write with 重量じゅうりょう.

重おもい (omoi) vs 思おもい (omoi): same sound, different word

Both words are pronounced おもい. They are written differently and mean very different things.

Word Reading Meaning Grammar
重おもい おもい heavy i-adjective
思おもい おもい a thought, a feeling noun
思い出おもいで おもいで a memory noun

思おもい comes from the verb 思おもう, "to think or to feel." It is the noun you meet in phrases like 思おもいがけない and in 片思かたおもい. If your goal is to understand the verbs, start with omou and kangaeru, and for remembering, see remember in Japanese.

In writing, the kanji settles everything. In speech, context does. "気きが重おもい" is dread, while "思おもいが重おもい" would sound like a strange mix of the two. If a sentence has an adjective ending in い that connects to a noun, it is almost certainly 重おもい.

Common mistakes

  • Saying 重おもいの荷物にもつ. There is no の between an i-adjective and its noun. Say 重おもい荷物にもつ.
  • Conjugating the negative like a na-adjective. 重おもいじゃない is wrong. The negative is 重おもくない.
  • Mixing up 重おもい and 思おもい. If you mean "heavy," it is 重じゅう. If you mean "a thought or feeling," it is 思おもい.
  • Choosing 軽かるい when you mean "light" as in lamp or sunlight. That is 光ひかり or 明あかるい, not 軽かるい.
  • Calling a person 重おもい to their face. It is a criticism. Save it for talking about a third party, and even then, be kind.

Practice

Build each answer before opening it. Questions 4 and 5 are a pair — the same noun with and without the extra の.

1. Say "This bag is heavy" in polite Japanese.

Show answer

このかばんは重おもいです — 重おもい is an i-adjective, so it ends in です to be polite.

2. Make 重おもい negative in the plain form.

Show answer

重おもくない — drop the final い and add くない, as with any i-adjective.

3. Say "It was heavy" in the plain form.

Show answer

重おもかった — drop い and add かった for the past.

4. Which is correct for "heavy luggage": 重おもい荷物にもつ or 重おもいの荷物にもつ?

Show answer

重おもい荷物にもつ — an i-adjective connects straight to the noun. This is the pair to question 5.

5. Why is 重おもいの荷物にもつ wrong, and when does 重おもいの appear at all?

Show answer

の does not go between an i-adjective and a noun. 重おもいの appears only when the adjective replaces the noun, as in 重おもいのはこっち, "the heavy one is this one."

6. Combine "this bag is heavy" and "it was hard" with て: 重おもい + 大変たいへんだった.

Show answer

重おもくて、大変たいへんだった — the て-form of an i-adjective replaces い with くて.

7. You dread tomorrow's meeting. Which expression do you use: 気きが重おもい or 気きが軽かるい?

Show answer

気きが重おもい — a heavy heart means dread. 気きが軽かるい means you feel relieved or free from worry.

8. You want only something small for lunch. Say "something light is fine."

Show answer

軽かるいものでいいです — 軽かるい describes the food as light, not heavy, and でいいです means "that is fine."

9. How do you ask "How many kilos is this?"

Show answer

これ、何なにキロですか — 何なにキロ asks for the number of kilos. You can also say 重おもさはどのくらいですか.

10. Is the 軽かるい in 軽かるい荷物にもつ related to the 光ひかり in 光ひかる?

Show answer

No. 軽かるい (かるい) is about weight; 光ひかり (ひかり) is about light you can see. English uses one word for both, Japanese does not.

Describe a heavy bag and a heavy heart, 気きが重おもい, in a trial lesson and listen to how 重おもい and 思おもい sound the same.

FAQ

Is "heavy" in Japanese hiragana おもい or おもたい? Both exist. おもい is the standard word, and おもたい is a slightly softer, more spoken variant of the same meaning.

Can I use 重おもい for heavy rain? No. Heavy rain is 大雨おおあめ (おおあめ). 重おもい stays with weight, moods, and serious matters like 重おもい病気びょうき, "a serious illness."

What is the difference between 重おもい and 重要じゅうよう? 重おもい is an adjective for physical or emotional weight. 重要じゅうよう (じゅうよう) is a na-adjective meaning "important," and the two share the kanji 重じゅう.

How do I say "heavy" in a polite and a casual way? Polite: 重おもいです. Casual: 重おもいね or just 重おもい. Both come from the same dictionary form.

Is 軽かるい always a compliment? No. For weight, food, or exercise it is neutral or positive. For a person, 軽かるい人ひと or 口くちが軽かるい is a criticism.

Vocabulary from this article

Tap the block to select all of it, then copy. In Anki: File → Import, note type Basic, separator Tab — the first column becomes the front, the second the back.

重い	おもい — heavy
軽い	かるい — light (in weight)
荷物	にもつ — luggage, baggage
気が重い	きがおもい — to feel heavy-hearted
責任	せきにん — responsibility
体	からだ — body
重たい	おもたい — heavy (softer, spoken)
重さ	おもさ — weight
重量	じゅうりょう — weight (formal, written)
口が軽い	くちがかるい — loose-lipped
思い	おもい — a thought, a feeling

I'm Yuuki, a Japanese teacher based in Tokyo. I've taught on italki as a Top 1% teacher and watched over 1,500 anime, so most of the example sentences on this blog come from lines I've actually heard students ask about — including this one, where 重おもい and 思おもい sound identical and trip up learners. For practice with feedback, Book a trial lesson · $13, or work through Japanese practice exercises first.

Sources: the author's own lessons and standard reference grammars.

More drills like the ones above, plus a timed JLPT-style mock test: Practice · N5 · Read something at this level: JLPT N5 stories with audio

More “Describing Things: Japanese Adjectives & Opposites” articles →

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