背

背 is derived from 北 (buk, “north”).

北 originally depicted two people standing back to back. This gave the meaning “to turn away, to oppose,” before being semantically shifted to “north.”

Once 北 was primarily associated with “north,” a new character 背 was created to preserve the original meaning of “back.”

To clarify the sense of the body part, the flesh radical 月 (variant of 肉, “flesh”) was added to 北.

Thus, 背 is both a compound ideograph and a phono-semantic character, highlighting both the physical body (flesh) and the semantic root in 北 (“back-to-back”).

In Korean, 배 (背) retains the meanings “back, to turn one’s back, to carry on the back,” and is very productive in compounds:

배신 (背信) – betrayal (lit. “turning back on trust”)

배반 (背反) – betrayal, treachery

배낭 (背囊) – backpack

배부 (背負) – to carry on the back, to shoulder

등배 (背) – the back (as a noun, in classical/compound usage)

Note: In Korean, 배 (背) can sometimes be confused with the native word 배 (腹, stomach/belly) because of identical pronunciation. For example, 배갑 (背甲, turtle shell, “carapace”) may mistakenly be understood as “belly shell.”