party in full swing; party at its peak
Describes a lively party or banquet at its most enjoyable moment. Often used in set phrases like 宴もたけなわですが to signal a transition or closing.
The party is in full swing, but let's call it a night soon.
When the party was at its peak, he suddenly started singing.
Rare kanji spelling using 酣; the kana form is strongly preferred.
The phrase combines 宴 (banquet) with たけなわ (height, peak). たけなわ is of uncertain origin, possibly from 丈 (height) + 直 (straight) or related to 盛り (peak). The expression is idiomatic and not derived from a single kanji compound.