ETYM Italian, from Latin aër. Related to Air.
An elaborate song for solo voice.
Melody, especially solo for voice in opera or oratorio.
Melodic solo song of reflective character, often with a contrasting middle section, expressing a moment of truth in the action of an opera or oratorio. Pioneered by Giacomo Carissimi, it became a set piece for virtuoso opera singers, for example Handel’s aria “Where’er you walk” from the secular oratorio Semele 1744 to words by William Congreve. As an instrumental character piece, it is melodious and imitative of a vocal line.

1. An E province of ancient Persian Empire; district now in NW Afghanistan and E Iran.
2 — see HERAT.