어도

even if; also "may, is allowed"

Says the outcome holds regardless: 넣어도 is "no matter what you put in", 봐도 is "however much I look", 말하지 않아도 is "even without saying it". Fused onto the verb stem, so it hides inside the word. It also builds the standard way to give permission — -어도 되다, literally "even doing it is fine": 써도 됩니다 is "you may use it" and 써도 돼요 is "go ahead and use it". After stems with a bright vowel the same ending is spelled -아도.