Under your nose means right in front of you the whole time, yet unnoticed. It was under your nose, happened under your nose, right under your nose.
It carries a mild reproach, since the thing was there to be seen. It is used both of what you failed to find and of what somebody did while you watched.
1phraseunder your noseRight in front of you the whole time, yet unnoticed.
“The keys were under your nose on the hall table all morning.”
under your nose is a phrase.
Also accepted in games: right under your nose
Practised in Idioms