In biology, culling is the process of segregating organisms from a group according to desired or undesired characteristics. In animal breeding, it is the process of removing or segregating animals from a breeding stock based on specific trait.

What does it mean when you cull something?

2 : to reduce or control the size of (something, such as a herd) by removal (as by hunting or slaughter) of especially weak or sick individuals The town issued hunting licenses in order to cull the deer population.

What does cull mean in slang?

cull (plural culls) (slang, dialectal) A fool, gullible person; a dupe.