脑袋
nǎodài · HSK 4
head
🧠 脑袋 = 脑 (brain) + 袋 (bag) — the bag that holds your brain
脑 means brain and 袋 means bag or sack (same 袋 as in 口袋 pocket and 袋鼠 kangaroo). So 脑袋 is literally the brain-bag, a colloquial word for head or noggin.
袋 — 代 (dài, phonetic) + 衣 (clothing)
袋 is a semantic-phonetic compound. The bottom 衣 'clothing/cloth' gives the meaning, since bags were originally made of cloth, while 代 on top supplies the sound 'dài'. It has long meant 'bag, sack, pouch'.