What does 海 mean in Japanese?
海 means sea or ocean. The left side of the kanji is the water radical 氵, which signals its aquatic meaning. The right side 毎 is mainly a phonetic component here, helping shape the on’yomi カイ rather than adding the core meaning.
For learners, 海外 (kaigai, overseas/abroad) is probably the single most important compound to learn first: 外 means ‘outside,’ so 海外 literally means ‘outside the seas’ — abroad. Almost any conversation about international matters uses 海外.
Reading
On’yomi: カイ (kai)
Kun’yomi: うみ (umi)
Basic Information
| Kanji | 海 |
|---|---|
| Meaning | sea, ocean |
| Stroke Count | 9 |
| JLPT Level | N4 |
How to Understand This Kanji
うみ (kun’yomi) is the everyday standalone word: 海に行く (go to the sea). カイ (on’yomi) dominates in compounds. 海外 is used for all things international — not just the sea itself but the world beyond Japan’s coastline. 海苔 (nori, seaweed) is an important exception: its reading is のり, not a predictable うみのり or かいのり. Food compound readings in Japanese often need to be memorised as fixed forms.
Common Words
- 海（うみ / umi） — sea, ocean
- 海外（かいがい / kaigai） — overseas, abroad
- 海岸（かいがん / kaigan） — coast, beach, seashore
- 海水浴（かいすいよく / kaisuiyoku） — sea bathing, swimming at the beach
- 日本海（にほんかい / nihonkai） — Sea of Japan
- 海苔（のり / nori） — seaweed (used in sushi and rice balls)
Example Sentences
-
夏に海で泳ぎたいです。
なつにうみでおよぎたいです。 / Natsu ni umi de oyogitai desu.
I want to swim in the sea in summer.
-
海外旅行に行ったことがありますか？
かいがいりょこうにいったことがありますか？ / Kaigai ryokou ni itta koto ga arimasu ka?
Have you ever been on an overseas trip?
-
海岸を散歩しました。
かいがんをさんぽしました。 / Kaigan o sanpo shimashita.
I took a walk along the coast.
When Learners Usually See This Kanji
海外 (kaigai) deserves special attention because it appears in such a wide range of contexts: 海外旅行 (overseas trip), 海外留学 (study abroad), 海外出張 (overseas business trip), 海外在住 (living abroad). Knowing 海 (sea) + 外 (outside) makes the compound immediately transparent.
海苔 (nori) is a reading trap. The expected pattern would give うみのり or かいのり, but the actual reading is のり. This is a fixed food word with its own pronunciation — a common phenomenon with Japanese food vocabulary that learners need to memorise directly.
The water radical 氵 (three dots on the left) appears in many water-related kanji: 水, 泳, 海, 洗, 泊, 温. Recognising it as a semantic indicator helps with reading new kanji: if you see 氵 on the left, the meaning is likely connected to water or liquid.
Summary
海 means sea or ocean and unlocks key vocabulary including 海外 (overseas), 海岸 (coast), and 海水浴 (sea bathing), with the water radical 氵 as a visual cue.