Meronym is a semanitk relation concept used in linguistics. A meronym denotes a constituent part of, or a member of something. That is,

X is a meronym of Y if Xs are parts of Ys, or

X is a meronym of Y if Xs are members of Ys.

For example, 'finger' is a meronym of 'hand' because a finger is part of a hand. Similarly 'wheel' is a meronym of 'auto'.

Meronymy is the opposite of holonymy. A closely related concept is that of mereology, which specifically deals with part/whole relations and is used in logic. It is formally expressed in terms of first-order logic.

A meronym means part of a whole. A word denoting a subset of what another word denotes is a hyponym.