Why is the ninth month called September?
"main part of a church," 1670s, from Medieval Latin navem (nominative navis) "nave of a church," from Latin navis "ship" (see naval), on some fancied resemblance in shape.
"hub of a wheel," Old English nafu, from Proto-Germanic *nabo- (cf. Old Saxon naba, Old Norse nöf, Middle Dutch nave, Dutch naaf, Old High German naba, German Nabe), perhaps connected with the root of navel on notion of centrality (cf. Latin umbilicus "navel," also "the end of a roller of a scroll," Greek omphalos "navel," also "the boss of a shield").