Definition valency in British English

a measurement of the ability of a chemical element to combine with other elements. The measurement is a number that shows how many atoms of the element combine with a single atom of the element hydrogen.

all the phrases and clauses that typically follow a verb. For example, the valency of a linking verb like 'be' typically involves a noun group, an adjective group, or a prepositional phrases such as 'in a muddle' in the sentence 'Oh dear, you are in a muddle, aren't you?'