Why is the ninth month called September?
1590s, from Latin multifarius "manifold," from multifariam (adv.) "on many sides; in many places or parts," perhaps originally "that which can be expressed in many ways," from multi- "many" (see multi-) + -fariam, adverbial suffix (cf. bifariam "in two places"), from PIE *dwi-dhe- "making two." Related: Multifariously; multifariousness. Earlier forms of the word in English were multiphary (adv.); multipharie (adj.), both mid-15c.