D defs.my
Entry 1 sense Webster, 1913

nincompoop

/nĭng'-kəm-po͞opˌ/ · nin·com·poop · IPA /ˈnɪŋkəmˌpup/
01 n. A fool; a silly or stupid person.
  1. 1.
    A fool; a silly or stupid person.[Law]
    “An old ninnyhammer, a dotard, a nincompoop, is the best language she can afford me.” Addison.