Several parts combine into one character.

頭 is a phono-semantic character: 頁 (head) for meaning and 豆 (bean) for sound. 頁 was originally a picture emphasizing a person's head, and 豆 lends the sound "dou/du." The topmost part of the body, the head, is its core sense.

The simplified form is greatly reduced to 头 — based on a cursive form that drops both 頁 and 豆, so it looks nothing like traditional 頭. The form splits sharply by mode.

Korean hanja-sound "du": 頭腦 (dunoe, brain), 先頭 (seondu, the lead / front), 念頭 (yeomdu, mind / thought), 龍頭 (yongdu, dragon head), 沒頭 (moldu, absorption). It is also a counter for large animals — one 頭 (du) of cattle.

Mandarin: tóu, 2nd tone (often neutral). 头 (tóu, head), 头发 (tóufa, hair), 开头 (kāitóu, beginning), 街头 (jiētóu, street corner), 一头牛 (yì tóu niú, one head of cattle). It is also a common suffix marking direction or end — 上头, 里头, 后头.

Japanese: on-readings トウ (tō) and ズ (zu), kun あたま (atama) and かしら (kashira). 頭 (atama, head), 頭脳 (zunō, brain — a ズ reading), 先頭 (sentō, the lead), 音頭 (ondo, a lead-chant), 一頭 (ittō, one animal). Large animals are counted 一頭, 二頭.

Memory aid: a head (頁) plus the sound bean (豆) — the topmost of the body, the head.