adverb, noun
100 percent; completely; fully
Colloquial abbreviation of 百パーセント, used adverbially or as a noun to mean 'totally' or 'without reservation'.
その計画には１００パー賛成だ。
I'm 100 percent in favor of that plan.
今日の仕事は１００パー終わった。
Today's work is completely finished.