Onomasiology (from onomaz? 'to name', which in turn is from ???u? onoma 'name') is a branch of linguistics concerned with the question "how do you express X?" It is in fact most commonly understood as a branch of lexicology, the study of words (although some apply the term also to grammar and conversation).

Onomasiology, as a part of lexicology, starts from a concept which is taken to be prior(i.e. an idea, an object, a quality,