In ancient times, drums made of alligator skin were used for ritual ceremonies and warfare.
Tips
usage
tuó names the Chinese alligator (Alligator sinensis), one of only two surviving alligator species in the world. Two compounds: 鼍龙 (literally 'tuó-dragon' — the colloquial Chinese name; in folk tradition the alligator's roar was thought to be a dragon calling rain), 扬子鳄 (Yangtze crocodile — the modern zoological term, more common in everyday usage). The historical compound 鼍鼓 names a drum stretched with alligator hide — Han bronzes show such drums in ritual processions.
register
Outside zoology and classical references, the everyday word for the animal is 扬子鳄. 鼍 appears mainly in literary writing, place names, and folklore — and in Mozi's famous list 鱼鳖鼋鼍 'fish, turtle, soft-shell, alligator' in his pacifist parable 《公输》.
Components
radical
黽miǎn
toad / amphibian (radical)
Bottom amphibian / reptile radical (Kangxi #205) — originally a pictograph of a frog or toad, later generalised to cover amphibians and large water-dwelling reptiles. Anchors the meaning: 鼍 is a great water reptile. Same radical heads 鼋 (giant soft-shelled turtle), 鳖 in its older form.
Top phonetic — a fused shape historically derived from 单 (single) supplying the sound (dān → tuó is irregular by modern Mandarin but was regular in the Old Chinese phonetic series). The traditional form 鼉 shows the phonetic more clearly.