In Celtic, name Ally means – Diminutive of Alan: Harmony, stone, or noble. Also fair, handsome. Originally a saints name, it was reintroduced to Britain during the Norman Conquest, remained popular throughout the Middle Ages, and was revived in the 19th century.. Other origins for name Ally include – Celtic, American, French, English, Gaelic. Name Ally is most often used as a boy name or male name.