背后
bèihòu · HSK 3
behind
🔙 背 = back (of body) + 后 = behind/after
背 means the back of the body; 后 means behind or after in time/space. Together they form the noun meaning the rear side or the area behind something. Often used figuratively for what happens 'behind the scenes.'
背 — north 北 (phonetic) + flesh 月/肉
Originally a phono-semantic compound: 月 (a form of 肉, 'flesh/body') gives the meaning 'back of the body,' while 北 supplies the sound. Interestingly, 北 itself depicted two people back-to-back and once meant 'back'; when it was borrowed for 'north,' 背 was created with the flesh radical to keep the original sense.
后 — 厂 cliff + 一 + 口 mouth
Originally depicted a ruler or sovereign issuing commands, showing a figure with a mouth giving orders. It came to mean 'queen' or 'empress.' In modern simplified Chinese, 后 also absorbed the meaning 'behind/after' from the traditional character 後, so context decides which sense applies.