Given an entity as input, output another entity which is part of the input entity. These are entities of meronym. In linguistics, meronymy is a semantic relation between a meronym denoting a part and a holonym denoting a whole. In simpler terms, a meronym (i.e., output entity) is in a part-of relationship with its holonym (i.e., input entity).

Q: papillae

A: follicle
****
Q: snap pea

A: pod
****
Q: coal gas and motor exhaust fume

A:
carbon monoxide
****