taru-adjective, adverb taking the 'to' particle
triumphant; exultant; in high spirits
Describes a proud, elated state, often used in the phrase 意気揚々 (いきようよう) meaning 'in high spirits' or 'triumphantly'. Typically appears as a たる adjective or adverb with と.
See also: 意気揚々
彼は意気揚々と会場を後にした。
He left the venue in high spirits.
優勝したチームは揚々と引き揚げていった。
The winning team withdrew triumphantly.
A common set phrase meaning 'in high spirits' or 'triumphantly'; 揚々 alone is less frequent and more literary.
From 揚 (あげる, 'to raise') reduplicated, suggesting a raised or elated state. The exact historical derivation is uncertain.