背 refers to height/stature or the back of the body.
HEIGHT EXPRESSIONS:
BACK EXPRESSIONS:
- 背中: back (of body) - most common
- 背を向ける: to turn one's back
- 背を伸ばす: to straighten one's back
- 背を押す: to push from behind; to encourage
RELATED WORDS:
IDIOM:
背に腹は代えられない: necessity knows no law