I love almost all fruits. Especially tomatoes. Tomatoes??? YES - the tomato is a fruit!
The definition of a vegetable: an edible part of a plant that comes from the leaf, stem or root.
The definition of a fruit: an edible part of a plant that comes from the flower. The flower produces the seeds, so if there are seeds, it comes from the flower, and thus it is a fruit. Therefore the tomato and cucumber are fruits. Your grocer puts tomatoes and cucumbers in the vegetable section because they are not sweet like most other fruits.
An interesting saying goes: "Knowledge is knowing that the tomato is a fruit. Wisdom is not adding tomatoes to a fruit salad."