/mus"tang/ , n.
1. a small, hardy horse of the American plains, descended from Spanish stock.
2. U.S. Navy Slang. a naval officer who received his commission while still an enlisted man.
v.i.
3. to round up wild horses, esp. in order to sell them illegally to slaughterhouses.
[ 1800-10, Amer.; mestengo stray or ownerless beast, n. use of masc. adj.: pertaining to a mixed lot of beasts, equiv. to mest ( a ) such a mixed lot ( animalia ) mixta mixed (beasts), neut. pl. adj., taken as fem. sing. noun; see MIXED) + -engo adj. suffix ]