Like gillyp says, someone who consumes a mostly vegetarian diet but does eat fish. I think it's on the grounds that fish are different in some way from regular cows and sheep... I used to know a lady who was pescetarian back in the day on the grounds that cows and sheep are factory farmed but fishermen and women had to actually go 'hunt' the fish, although of course most fish are raised in fishfarms these days. I know another guy who eats fish on the grounds that they have a different nervous system than your average mammal and don't suffer as much, although as a vegetarian myself, I personally wouldn't like to be suffocated to death, as most fish are when they are caught. I do think that fishing is less environmentally unfriendly in terms of deforestation and methane production than the farming of cows and sheep, so I guess there is some kind of point there, although personally I wouldn't eat fish in a million years on ethics grounds and I think pescetarians are a bunch of fence-sitting wussies. :)