Source : Webster's Revised Unabridged Dictionary (1913)

Substrate \Sub"strate\, n.
   A substratum. [R.]

Substrate \Sub"strate\, a.
   Having very slight furrows. [R.]

Substrate \Sub*strate"\, v. t. [L. substratus, p. p. of
   substrahere. See {Substratum}.]
   To strew or lay under anything. [Obs.]

         The melted glass being supported by the substrated
         sand.                                    --Boyle.

Source : WordNet®

substrate
     n 1: the substance acted upon by an enzyme or ferment
     2: any stratum lying underneath another [syn: {substratum}]

Source : Free On-Line Dictionary of Computing

substrate
     
         The body or base layer of an {integrated circuit},
        onto which other layers are deposited to form the circuit.
        The substrate is usually Silicon, though Sapphire is used for
        certain applications, particularly military, where radiation
        resistance is important.  The substrate is originally part of
        the {wafer} from which the {die} is cut.  It is used as the
        electrical {ground} for the circuit.
     
        (1996-04-07)