/mas"tif, mah"stif/ , n.
one of a breed of large, powerful, short-haired dogs having an apricot, fawn, or brindled coat.
[ 1300-50; ME mastif, perh. extracted from AF masti ( n ) s (taken as * mastifs ), pl. of OF mastin canis ) * ma ( n ) suetinus, deriv. of L mansuetus tame, mild (see MANSUETUDE) ]