Find the odd number / letters / word from the given alternative.

The odd one out is potato. The other four are fruits, while potato is a vegetable.

Tomato is a fruit because it is a seed-bearing structure that develops from the ovary of a flowering plant, whereas a vegetable is an edible plant or part of a plant other than a sweet fruit or seed. Gourd, brinjal, and cucumber are all fruits.

Potatoes are tubers, which are underground plant stems that store food. They are not fruits because they do not develop from the ovary of a flowering plant.