adverb taking the 'to' particle, taru-adjective
vigilantly watching for an opportunity; with an eagle eye
Describes a state of watching intently and patiently, like a tiger eyeing its prey, waiting for the right moment to act. Often used with と and verbs like 狙う or 見守る.
彼は虎視眈々と社長の座を狙っている。
He is vigilantly eyeing the president's position, waiting for his chance.
ライバル企業が虎視眈々と市場参入の機会をうかがっている。
Rival companies are eagerly watching for an opportunity to enter the market.