Synesis is a grammatical term, also known as 'constructio ad sensum'. It is a type of a scheme.

It is Latin for a construction in which a word takes the gender or number not of the word with which it should regularly agree, but of some other word implied in that word. It is effectively an agreement of words according to the sense, and not the grammatical form.

Example:

If the band is popular, they will play next month.

Here, the plural pronoun they refers to the singular noun band. One can think of the antecedent of they as an implied plural noun such as musicians.

Linguistic morphology