culling actually means selecting out from a group on the basis of some criteria. harvested lobsters with one claw have less commercial value so they are separa

culling actually means selecting out from a group on the basis of some criteria. harvested lobsters with one claw have less commercial value so they are separated out. They are sold more cheaply and called "culls". A difficult entry level university course in an academic department like Chemical Engineering could be used to cull the class of students down to only those who are serious about pursuing the field; in such a case, the culls are not killed. it's the nature of metonymy https://en.wikipedia.org/wiki/Metonymy https://en.wikipedia.org/wiki/Metonymy that the word cull can take on extra meanings depending on the context.