synesisn.

1722 S. Lowe Specimen Lat. Gram. 1 in Proposal Perfecting Lat. Gram. Figures of grammar...In Syntax: Ellipsis, Synesis, & Pleonasmus.

1770 J. Barr Pract. Gram. Lat. Tongue 219 Synesis, when the Construction does not refer to the word, but the sense or meaning of it.

1872 J. H. Allen & J. B. Greenough Lat. Gram. for Schools & Colleges ii. 103 When a word takes the gender or number of some other word implied in that with which it should agree, this use is called Synesis.

1923 Classical Philol. 18 289 The multiplicity of instances of synesis that occur in both Greek and Latin shows that they are not all inadvertences or inaccuracies, as some grammarians and editors are inclined to characterize them... Many uses are so natural that even we, with our formal attitude toward grammar, often pass over them without noting anything peculiar about them.

1967 Hispania 50 117/2 Perhaps the most common device of them all is the use of a synesis—the cause of so many deviations where the construction is in accordance with the sense rather than syntactic orthodoxy.

1998 B. A. Garner Dict. Mod. Amer. Usage 417/1 Majority is sometimes a collective noun that takes a singular verb, but sometimes (through synesis) it's a plural demanding a plural verb.