A person who does not buy meat (from either restaurants or grocery stores) but will eat meat if it has already been prepared.

The inclusion of market refers to the fact that this person's buying behaviour (from the market's perspective) is like a vegetarian.
At a house party:
Person 1: Did you just have a meat pie? I thought you didn't want to have meat at the restaurant last week?

Person 2: I don't buy meat, but if it's already been purchased I'm ok with having it.

Person 1: Oh! So you're like a Market Vegetarian?

Person 2: Exactly

Person 1: What a hipster
by angularmerkel September 30, 2018
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