深(ふか)い

ふかい

i-adjective

deep; profound

Conjugation

	Affirmative	Negative
Present	深(ふか)い	深(ふか)くない
Past	深(ふか)かった	深(ふか)くなかった
て form	深(ふか)くて	深(ふか)くなくて
Adverbial	深(ふか)く	—
Conditional ば	深(ふか)ければ	深(ふか)くなければ
Conditional たら	深(ふか)かったら	深(ふか)くなかったら

1. deep (physical depth)

Describes something with great depth, such as water, a hole, or snow.

このプールは深(ふか)いから、気(き)をつけて。

This pool is deep, so be careful.

Physical depth

この川(かわ)は深(ふか)い。

This river is deep.

雪(ゆき)が深(ふか)くて歩(ある)けない。

The snow is too deep to walk.

穴(あな)は思(おも)ったより深(ふか)かった。

The hole was deeper than I thought.

深(ふか)い傷(きず)を負(お)った。

I suffered a deep wound.

2. profound, deep (abstract)

Describes deep meaning, understanding, relationships, or feelings.

深(ふか)い意味(いみ)がある。

It has a deep/profound meaning.

Abstract meaning

二人(ふたり)は深(ふか)い関係(かんけい)にある。

The two have a deep relationship.

深(ふか)い愛情(あいじょう)を感(かん)じる。

I feel deep affection.

この問題(もんだい)は深(ふか)い。

This problem is deep/complex.

深(ふか)い知識(ちしき)を持(も)っている。

They have profound knowledge.

深(ふか)い眠(ねむ)りについた。

I fell into a deep sleep.

深(ふか)い感謝(かんしゃ)の気持(きも)ちを伝(つた)えたい。

I want to express my deep gratitude.

3. dense, thick

Describes dense fog, thick forest, or dark/rich colors.

霧(きり)が深(ふか)い朝(あさ)だった。

It was a morning with thick fog.

Dense/thick meaning

深(ふか)い森(もり)に迷(まよ)い込(こ)んだ。

I got lost in a dense forest.

深(ふか)い緑(みどり)の葉(は)っぱ。

Leaves of a deep green color.

深(ふか)い青(あお)の海(うみ)。

A sea of deep blue.

深(ふか)い闇(やみ)に包(つつ)まれた。

It was enveloped in deep darkness.

4. late (time of night)

Describes late hours of the night.

夜(よる)深(ふか)くまで勉強(べんきょう)した。

I studied until late at night.

Time expression

夜(よる)が深(ふか)くなった。

The night grew late.

深夜(しんや)まで働(はたら)いた。

I worked until late at night.

夜(よる)深(ふか)くに電話(でんわ)が鳴(な)った。

The phone rang late at night.

深(ふか)い夜(よる)の静(しず)けさの中(なか)で本(ほん)を読(よ)んでいた。

I was reading a book in the stillness of the late night.

Usage

深(ふか)い covers a wide span of meanings that English splits between 'deep,' 'profound,' 'thick/dense,' and 'late.' The common thread is extent measured inward or downward rather than across. It works both as a noun modifier (深(ふか)い川(かわ)) and as a predicate (川(かわ)が深(ふか)い).

Physical depth: water, holes, snow, wounds
Abstract profundity: meaning, knowledge, relationships, emotions
Density or richness: fog, forest, colors
Late night: 夜(よる)が深(ふか)い, 深(ふか)い夜(よる)

Forms

Adverbial: 深(ふか)く (深(ふか)く考(かんが)える, to think deeply)
Noun of measurement: 深(ふか)さ (depth as a quantity)
Noun of quality: 深(ふか)み (depth in the sense of richness or a deep spot)
Paired verbs: 深(ふか)まる (to deepen, intransitive), 深(ふか)める (to deepen, transitive)

Common collocations

深(ふか)い意味(いみ): a deep meaning
深(ふか)い関係(かんけい): a close, deep relationship
深(ふか)い眠(ねむ)り: a deep sleep
深(ふか)い感謝(かんしゃ): deep gratitude
霧(きり)が深(ふか)い: the fog is thick
深(ふか)い森(もり): a dense forest

Similar words

浅(あさ)い: the direct antonym, shallow in both the physical and the abstract sense
濃(こ)い: also 'thick, dense,' but about concentration (strong tea, dark makeup); for colors, 深(ふか)い suggests richness while 濃(こ)い suggests intensity
奥深(おくぶか)い: profound only, never physical depth downward

Register

Neutral and usable at any level of politeness. The physical senses are everyday speech; the abstract senses (深(ふか)い洞察(どうさつ), deep insight) are more frequent in writing and formal speech.