um·bil·i·cus (ŭm-bĭlĭ-kəs, ŭm′bə-līkəs)
n. pl. um·bil·i·ci (-sī′)
1. See navel.
2. Biology A small opening or depression similar to a navel, as the hollow at the base of the shell of some gastropod mollusks, one of the openings in the shaft of a feather, or the hilum of a seed.
[Latin umbilīcus; see nobh- in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.