late 14c., "breadth," from Old French latitude (13c.) and directly from Latin latitudo "breadth, width, extent, size," from latus "wide," from PIE root *stele- "to spread" (cognates: Old Church Slavonic steljo "to spread out," Armenian lain "broad"). Geographical sense also is from late 14c., literally "breadth" of a map of the known world. Figurative sense of "allowable degree of variation" is early 15c. Related: Latitudinal.