The kanji used for males is 愛 (ai) meaning "love, affection" combined with 夫 (o) meaning "man, husband", 男 (o) meaning "male" or 雄 (o) meaning "hero, manly" and for females the kanji is 愛 (ai) meaning "love, affection" combined with 緒 (o) meaning "thread". Other kanji combinations are possible.
Possibly originated from the name of the Roman deity Aius. Documented for the first time in Roman era inscriptions in San Vicente de Alcántara (Badajoz), and in the 12th century in Iruña/Pamplona.