Several parts combine into one character.

體 originally added 豊 (ritual vessel) to 骨 (bone) — a body furnished with bone and flesh (23 strokes). The shinjitai and simplified scripts cut it down to 体, 人 (亻, person) plus 本 (root) — and "the root of a person is the body" fits the new shape beautifully.

So the form splits: traditional (ko/en/es) is 體, shinjitai (ja) and simplified (zh) are 体 — a sharp difference in stroke count (體 23 vs 体 7).

Korean hanja-sound "che": 身體 (sinche, body), 體育 (cheyuk, physical education), 全體 (jeonche, the whole), 物體 (mulche, object), 體驗 (cheheom, experience). Korea uses the traditional 體.

Mandarin: tǐ, 3rd tone. 身体 (shēntǐ, body), 体育 (tǐyù, sports), 体验 (tǐyàn, to experience), 具体 (jùtǐ, concrete), 体重 (tǐzhòng, body weight). Japanese: on-readings タイ (tai) and テイ (tei), kun からだ (karada). 体 (karada, body), 身体 (shintai, body), 全体 (zentai, the whole), 体育 (taiiku, physical education), 体裁 (teisai, form / appearance — a テイ reading). In Japanese 物体 geminates to buttai.

Memory aid: a person (亻) whose root (本) is the body — traditional with bone (骨), shinjitai as a person's root.