Na-adjective (keiyodoshi), Taru adjective, Adverb taking the 'to' particle
in high spirits; elated
Yojijukugo (four character compound)
「来年こそは一部上場だ」と、社長は意気軒高だ。You could see the elation in the president's face when he announced that our shares are going to be listed on the First Section of the TSE next year.
Also written 意気軒高【いきけんこう】