Usually a mother --but could be a childless woman (rare!)-- whose good mothering traits such as concern for others and knowing better get blown to massive Japanese-lizard proportions, thus rendering them annoying and complicated people with whom you don't want to spend a second longer than you must. An overbearing bitch of a mom who's always right. Combination of "mom"+"Godzilla." See also momster
"Did you see how Tammy cut up my meat for me and tell me how to save money by using coupons? She is such a momzilla!!!"