Why is the ninth month called September?
mid-14c. (transitive); late 14c. (intransitive), from Old French varier, from Latin variare "change, alter, make different," from varius "varied, different, spotted;" perhaps related to varus "bent, crooked, knock-kneed," and varix "varicose vein," from a PIE root *wer- (1) "high raised spot or other bodily infirmity" (cf. Old English wearte "wart," Swedish varbulde "pus swelling," Latin verruca "wart"). Related: Varied; varying.
vary var·y (vâr'ē, vār'ē)
v. var·ied, var·y·ing, var·ies
To make or cause changes in the characteristics or attributes of; modify or alter.
To undergo or show change.
To be different; deviate.