masc. proper name, Scottish, related to Irish Aonghus, a compound that may be rendered in English as "having solitary strength," or else "one choice, sole choice." From Celtic oen "one" (from PIE root *oi-no- "one, unique") + Old Irish gus "ability, excellence, strength, inclination," from Celtic root *gustu- "choice," from PIE root *geus- "to taste; to choose." Also the name of a former county in Scotland (said to have been named for an 8c. Pictish king of that name), hence a breed of cattle (1842) associated with that region.