The Collaborative International Dictionary of English v.0.48:

honker \honk"er\ (h[o^][ng]k"[~e]r), n.
   1. The nose; -- an informal terms used in the U. S. [WordNet
      sense 1] [informal]

   Syn: beak, hooter, nozzle, snoot, snout, schnozzle.
        [WordNet 1.5]

   2. Something that honks.
      [PJC]

   3. Specif. The common grayish-brown wild goose (Branta
      canadensis) of North America; the Canada goose. [WordNet
      sense 2]

   Syn: Canada goose, Canadian goose, Branta canadensis.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

honker
    n 1: a driver who causes his car's horn to make a loud honking
         sound; "the honker was fined for disturbing the peace"
    2: informal terms for the nose [syn: beak, honker, hooter,
       nozzle, snoot, snout, schnozzle, schnoz]
    3: common greyish-brown wild goose of North America with a loud,
       trumpeting call [syn: honker, Canada goose, Canadian
       goose, Branta canadensis]