Question

Define cohesive force.

Answer 1

do you know, why a droplet of water is spherical in shape. of course you said surface tension. but one more important fact is that cohesive force acts between them, as it is attractive in nature and same quantity in all directions , droplet becomes spherical in shape .

so, Let's define cohesive force !
cohesive force is a intermolecular force of like molecules of the same substance to stick each other due to attraction. or you can say in simple , cohesive force is attractive force exists between molecules of the same substance.