"oats," Northern English, late 13c., probably from Old Norse hafre, from Proto-Germanic *habron- (source also of Old Norse hafri, Old Saxon havoro, Dutch haver, Old High German habaro, German Haber, Hafer). Buck suggests it is perhaps literally "goat-food" and compares Old Norse hafr "he-goat." "Haver is a common word in the northern countries for oats." [Johnson]
"owner, possessor," late 14c., agent noun from have.