An Etymological Dictionary of Astronomy and Astrophysics

A large, usually tawny-yellow cat, Panthera leo, native to Africa and southern Asia, having a tufted tail and, in the male, a large mane (dictionary.com).

Etymology (EN): M.E., from O.Fr., variant of leon, from L. leon- (stem of leo), from Gk. leon.

Etymology (PE): Mid.Pers. šagr “lion;” cf. Parth. šarg; Sogd. šarγu “lion;” its O.Pers. and Av. forms are not extant. Šir may be cognate with Skt. kēsarin- “lion; literally maned,” from kēsar- “mane;” PIE *kaisar- “mane; hairs.” If so, šir could be related to PIE *kaisaraka-, provided that the the initial *kai- is dropped and *saraka- has transformed in *sarg, šarg, šir.