Why was "tantrum" trending last week?
"navel," 1610s, from Latin umbilicus "navel," from PIE root *(o)nobh- "navel" (see navel). In English, mostly confined to medical writing. Latin umbilicus is source of Spanish ombligo as well as Old French lombril, literally "the navel," from l'ombril, which by dissimilation became modern Fr. nombril (12c.).
umbilicus um·bil·i·cus (ŭm-bĭl'ĭ-kəs, ŭm'bə-lī'kəs)
n. pl um·bil·i·ci (-sī')