Although it may be surprising to many, cucumbers are botanically a fruit. While they are probably one of the last plants that we would think of as a “berry,” that is what they are botanically. (Specifically, they fall under the botanical subclassification of berries called a “pepo.”) This classification is because cucumbers have seeds inside them, are fleshy, were made from a single ovary, and don’t split open to spread their seeds everywhere. They are the “fruit” of the plant. However, this definition of fruits is essentially independent from our everyday definitions of “fruit” and “vegetable”. Cucumbers can be a fruit botanically and a vegetable culinarily, but the botanical definition doesn’t practically matter.
Practically, cucumbers are not fruits. In the culinary world, they are obviously considered to be vegetables. They are mainly eaten in leafy vegetable salads, not fruit salads. They are not sweet; they are largely flavorless. Although they are very wet, they are still crunchy and would not be considered juicy. The water in them is too plain to even be considered juice by some. These show that cucumbers are vegetables. If you put cucumbers in your berry pies, you should probably be committed. I have never heard of someone considering cucumbers to be fruits. They are vegetables.