The state of matter where the molecules are closest together is known as a solid.
In solids, the molecules are tightly packed together, usually in a fixed arrangement. This close proximity allows solids to maintain a definite shape and volume. The forces between the molecules in a solid are strong enough to hold them in place, giving solids their rigid structure.
In contrast, in liquids, the molecules are still close together but can move past one another, which allows liquids to take the shape of their container. In gases, the molecules are far apart and move freely, leading to a lack of definite shape or volume.
So, when we talk about states of matter, solids are the state where the molecules are closest together.