adverb taking the 'to' particle, taru-adjective
glaring covetously; watching eagerly for a chance
Literary and somewhat archaic; describes a predatory, intense gaze waiting for an opportunity. Often used in the set phrase 虎視眈々 (こしたんたん), 'watching like a tiger ready to pounce'.
See also: 虎視眈々
彼はライバル会社の動向を眈々と見つめていた。
He was glaring covetously at the rival company's movements.
虎視眈々とチャンスを狙う。
Watch eagerly for a chance like a tiger.
Irregular kanji usage; not standard.
A common four-character idiom using 眈々; means 'watching vigilantly for an opportunity like a tiger'. 眈々 alone is rarer and more literary.
The kanji 眈 means 'to glare' or 'to watch intently'. The reduplicated form 眈々 emphasizes the continuous, intense nature of the gaze. The exact historical derivation is uncertain, but it is a literary Chinese-derived expression.