Rare literary term, typically used in the form 氤氳たる (いんうんたる) to describe a scene or atmosphere brimming with energy and vitality. Not used in everyday speech.
The exact derivation is uncertain. The kanji 氤 and 氳 both relate to 'thick vapor' or 'abundant energy' in classical Chinese, and the compound is used in literary Japanese to describe a flourishing, energetic atmosphere.
