ni·date (n??d?t) intr.v. ni·dat·ed, ni·dat·ing, ni·dates To become implanted in the uterus. Used of a fertilized cell. [nid(us) + -ate.] ni·da?tion n. American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.nidate (n??de?t) vb (intr) (Physiology) embryol (of a new embryo) to undergo nidation, to implant (oneself) in the uterusCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014