Now this is from deep within my brain. Tomato in culinary terms is a veggie. It was officially made a veggie to escape taxes made on fruits back in the 18-19th century. By the true scientific definition it is a fruit. Fruit is part of a plant that bares the nutrients for the seeds to grow when they sprout.
I'm not totally right about it, but it's what I remember.
EDIT: Veggies are not entirely fruits. Veggies is a culinary term because it isn't sweet tasting like fruits are.