Translation guide
The English word "thick" covers several distinct concepts in Japanese, including physical thickness of objects, density of substances, and even figurative uses like close relationships. The most common Japanese equivalent is 厚い (atsui) for flat objects, but different words are used for cylindrical objects, liquids, vegetation, and more.
Describing something that has a large distance between its two opposite surfaces, like a thick book, a thick slice of bread, or a thick wall.
The standard word for 'thick' when referring to flat objects, layers, or things with depth. Used for books, walls, slices, carpets, etc.
この辞書はとても厚い。
This dictionary is very thick.
厚いステーキを焼いた。
I grilled a thick steak.
Emphasizes that something is very thick or bulky, often with a nuance of being heavy or substantial. Commonly used for books, documents, or thick slices.
Describing something that is thick in terms of girth or circumference, like a thick rope, a thick tree trunk, or thick arms.
Describing a liquid or gas that is dense, not watery, or flows slowly, like thick soup, thick fog, or thick smoke.
Used for liquids, gases, or colors that are dense, concentrated, or deep. Covers thick soup, thick fog, thick smoke, thick makeup, etc.
Describing something that grows densely, like thick hair, thick grass, or a thick forest.
Also used for dense growth of hair, fur, or vegetation. Note: 濃い covers both density of liquids/gases and density of growth.
Describing a strong, noticeable accent or a voice that is deep or husky.
Used for a thick (strong) accent. 強い訛り (tsuyoi namari) is the standard phrase.
Describing someone who is not easily affected by criticism or insults; figuratively thick-skinned.
Describing a very close, intimate relationship, often used in the phrase 'thick as thieves'.
The most natural way to express a close relationship. Literally 'on very good terms'.
あの二人はとても仲がいい。
Those two are thick as thieves.
Informal way to say someone is stupid or slow to understand.
Common phrase meaning 'stupid' or 'slow-witted'. Literally 'head is bad'.
彼はちょっと頭が悪い。
He's a bit thick.
厚い is for flat things (books, walls, slices). 太い is for cylindrical things (ropes, arms, trees). Using the wrong one sounds unnatural. For example, a thick book is 厚い本, not 太い本. A thick arm is 太い腕, not 厚い腕.
厚い (thick) and 暑い (hot weather) and 熱い (hot to the touch) are all pronounced あつい. Context usually makes it clear, but pay attention to the kanji.
分厚い本を読んでいる。
I'm reading a thick book.
Used for cylindrical or long objects that are thick in diameter: ropes, poles, arms, legs, tree trunks, etc.
彼は太い腕をしている。
He has thick arms.
この木の幹はとても太い。
The trunk of this tree is very thick.
I like thick soup.
濃い霧で前が見えない。
I can't see ahead because of the thick fog.
Describes a thick, syrupy, or gooey consistency, often for liquids like sauces or creams.
どろりとしたソースをかける。
Pour a thick sauce over it.
彼は髪が濃い。
He has thick hair.
Specifically for thick, overgrown vegetation or forests.
生い茂った森の中を歩いた。
We walked through the thick forest.
彼は強い訛りがある。
He has a thick accent.
Can describe a thick (deep, husky) voice, especially for men.
太い声で話す。
He speaks in a thick voice.
Idiomatic phrase meaning 'thick-skinned' or 'shameless'. Literally 'the skin of one's face is thick'.
彼は面の皮が厚い。
He is thick-skinned.
Means 'insensitive' or 'thick-headed', often used for someone who doesn't pick up on subtle cues.
彼は鈍感だから、皮肉が通じない。
He's so thick-skinned that sarcasm doesn't get through to him.
A more formal word for 'intimate' or 'close', suitable for describing relationships.
彼らは親密な関係だ。
They have a thick (close) relationship.
Means 'dull' or 'slow', often used for mental slowness.
彼は理解が鈍い。
He's thick (slow to understand).