noun
Refers to a person's or animal's back. In everyday speech 背中 is often more concrete, but 背 is common in set phrases such as 背を丸める and 背に負う.
寒くて背を丸めて歩いた。
I walked hunched over from the cold.
椅子の背にもたれて休んだ。
I rested by leaning against the back of the chair.
本の背に題名が書いてある。
The title is written on the spine of the book.
noun
Used especially in the pattern 背が高い／低い for a person's height. It refers to stature rather than altitude or the height of an object.
彼女はクラスでいちばん背が高い。
She is the tallest in the class.
noun
mountain ridge
A landform use that treats the ridge or crest of a mountain as its 'back.' 尾根 is the more explicit everyday word for a ridge.
道は山の背に沿って続いている。
The path continues along the mountain ridge.
A more concrete everyday word for the physical back of the body; 背 is shorter and common in fixed expressions and in the height sense 背が高い.
The measured height of a person, often used in formal or numerical contexts; 背 is the ordinary word in descriptions such as 背が高い.
A general word for the reverse or hidden side of something; 背 is used only for particular back, rear, or spine-like parts.
The normal specific word for a mountain ridge; 山の背 is a more image-based way to describe the same kind of feature.
A native Japanese noun read せ. The kanji 背 conventionally represents the meanings 'back' and, by extension, height and ridge-like backs; the exact historical derivation is not specified.