An Etymological Dictionary of Astronomy and Astrophysics

1. Any of the larger ocean mammals, excluding the porpoises and dolphins, that breathe through a blowhole on the top of their head and have front flippers, no hind limbs, and a flat horizontal tail.
   

2. The constellation → Cetus.

Etymology (EN): M.E., O.E. hwæl, cf. O.S. hwal, O.N. hvalr, Swed. val, M.Du. wal, Du. walvis, O.H.G. wal, Ger. Wal, probably cognate with L. squalus and Pers. vâl, as below.

Etymology (PE): 1) Mod.Pers. vâl, wâl, related to Mid.Pers. kar (mâhig) “whale (fish);” Av. kara- “a mythological fish;” also Mod.Pers. kuli “a kind of fish;” cf. L. squalus “a kind of large sea fish;” PIE (s)k^walo- “a large fish.”

2. Pers. nahang originally “crocodile,” from Mid.Pers. nihang “crocodile; hippopotamus,” ultimately from Proto-Iranian *ni-θanj- “to drag down,” since crocodiles drag down their preys
   underwater and drown them, from ni- “down, below,” → ni- (PIE) , + θanj- “to draw, pull” (cf. Pers. farhang; sanjidan, etc.).