The Collaborative International Dictionary of English v.0.48:

Decker \Deck"er\ (d[e^]k"[~e]r), n.
   1. One who, or that which, decks or adorns; a coverer; as, a
      table decker.
      [1913 Webster]

   2. A vessel or vehicle which has a deck or decks; -- used
      esp. in composition; as, a single-decker; a three-decker;
      a double-decker bus.
      [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

Decker
    n 1: English dramatist and pamphleteer (1572-1632) [syn:
         Dekker, Decker, Thomas Dekker, Thomas Decker]
    2: (often used in combinations) something constructed with
       multiple levels; "they rode in a double-decker bus"

U.S. Gazetteer Places (2000):

Decker, IN -- U.S. town in Indiana
   Population (2000):    283
   Housing Units (2000): 120
   Land area (2000):     0.261790 sq. miles (0.678032 sq. km)
   Water area (2000):    0.006597 sq. miles (0.017087 sq. km)
   Total area (2000):    0.268387 sq. miles (0.695119 sq. km)
   FIPS code:            17110
   Located within:       Indiana (IN), FIPS 18
   Location:             38.518391 N, 87.523814 W
   ZIP Codes (1990):     47524
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Decker, IN
    Decker