noun
General term for crocodilians; in everyday Japanese, ワニ covers both crocodiles and alligators without strict biological distinction.
オーストラリアでワニを見た。
I saw a crocodile in Australia.
ワニは爬虫類です。
Crocodiles are reptiles.
noun
Archaic meaning; in old Japanese, わに could refer to a shark or a large sea creature. Not used in modern Japanese.
古事記には、ワニが海の大きな魚として登場する。
In the Kojiki, ワニ appears as a large sea fish.
Outdated kanji form; not in common use.
The origin is uncertain. The archaic sense 'shark' may be the original meaning, with the shift to 'crocodile' occurring later. The kanji 鰐 is a phono-semantic compound, but the historical derivation of the word わに itself is unclear.