= bivalent, adj. n.

In various subjects: the quality of being bivalent; bivalency; spec. in Logic, principle of bivalence (see quots.).

†(a) a chromosome at zygotene; (b) = zygotene, n.; now rare.

Cytology. With pronunciation/ˈtrɪvələnt/. A multivalent consisting of three chromosomes.

Cell Biology. A multivalent consisting of four chromosomes.

Genetics. A multivalent involving five chromosomes.

Cell Biology. An association of three or more completely or partly homologous chromosomes during the first division of meiosis.

A nullisomic individual or variety.

Biology. Applied to homologous chromosomes united in pairs at the first division of meiosis. Hence as n.

= nullisomic, n. Also: the missing chromosome of a nullisomic individual or variety.