Translation guide
The English word "thin" covers many distinct concepts in Japanese, from describing people and objects to abstract qualities. The most common Japanese equivalents are 細い (hosoi) for slender objects, 薄い (usui) for flat things and weak concentrations, and 痩せている (yasete iru) for thin people. Choosing the right word depends on what is thin and in what way.
Describing a person or animal as having little body fat, or a body part as slender.
The standard way to say someone is thin (not fat). It implies a lack of body fat. Can be used positively or negatively depending on context.
She is very thin.
You've gotten thin lately.
Used for slender body parts like arms, legs, fingers, or waist. It emphasizes slimness in shape rather than overall body fat.
Loanword from English 'slim'. Often used positively for a slender figure, especially in fashion or advertising.
A slightly derogatory or childish term for a skinny person, like 'skinny' or 'scrawny'.
Describing something long and narrow in diameter, like a stick, string, or line.
The primary word for thin, long objects. Used for pencils, threads, roads, rivers, etc. Focuses on small cross-section.
Describing something flat and lacking thickness, like paper, a book, or a slice.
Used for flat things with little depth: paper, cloth, boards, etc. Also for thin layers.
Describing a substance that is watery, weak, or not thick, like soup, paint, or air.
Used for liquids, colors, flavors, etc. that are weak or diluted. Also for thin air at high altitudes.
Describing hair that is not dense, or balding.
Used for hair that is thinning or sparse. Also for eyebrows, beards, etc.
Describing a small number of people in a large space, or low turnout.
Commonly used for thin crowds, sparse attendance, or scattered objects.
Describing something insubstantial or flimsy, like an excuse or evidence.
Can be used figuratively for weak, thin excuses, smiles, or reactions.
細い is for long, slender things (pencils, legs, roads). 薄い is for flat things (paper, books) and for weak concentrations (thin soup, thin hair, thin air). 痩せている is specifically for people and animals being thin (low body fat). Using the wrong one can cause confusion: 薄い人 means a shallow/superficial person, not a thin person.
彼女は腕が細い。
She has thin arms.
You have thin fingers.
I want to maintain a slim figure.
あの子は痩せっぽちだ。
That kid is a skinny little thing.
Emphasizes that something is both thin and long. Often used for shapes like rectangles, leaves, or fingers.
It comes in a thin, long box.
Please write on thin paper.
This book is thin so I can read it quickly.
This soup tastes thin/weak.
The air is thin on the mountain top.
Means watery, thin, or lacking body. Often negative when describing food or drink.
This curry is thin/watery.
My father's hair has gotten thin.
Means sparse, thin, scattered. Can describe hair, vegetation, attendance, etc.
His beard is thin/sparse.
The audience was thin/sparse.
Literally 'few people passing', used for thin traffic or empty streets.
The streets are thin/empty at night.
His excuse is thin/weak.
Means weak; often used for thin arguments or evidence.
That evidence is thin/weak.
thin book (not thick)
thin person (not fat)
Do not use 細い to describe a person's overall body type. 細い人 means a person with a slender build (narrow frame), not necessarily thin. To say someone is thin (not fat), use 痩せている.