1.verbTo grasp or take hold of (an object) suddenly, forcibly, or tightly.
"The child seized upon the cat's tail as soon as it was within reach."
2.verbTo take up, embrace, enact, or turn eagerly to (a plan, idea, ideology, cause, practice, method, etc.); to grasp, understand, and accept quickly; to adopt wholeheartedly or vigorously.
"I heard her ideas and seized upon them immediately."
3.verbTo take possession of or claim (an idea, person, event, etc.) as one's own; to assimilate, absorb, annex, co-opt.
"After the controversy of her public statement, she has been the darling of right-wing groups who have seized upon her as the poster child of their cause."