to fail to participate in something; to fail to take part in something. I'm sorry I missed out on the ice cream.I lost out on getting in the class photo because I was sick that day.
to fail to use or enjoy an opportunity Other people my age are married and have families, and I am beginning to feel I am missing out.We missed out on a chance to get a cheaper mortgage.
To be unable or fail to participate in something: I missed out on last month's concert because I was out of town. There's a lot going on at the fair, so set aside the whole day or you'll miss out!