1. The specific molecule an enzyme acts upon.
2. A stationary surface upon which organisms, cells or chemicals can attach.
   For example:
   • cells in culture on a plastic or glass substrate
   • oyster larvae settling on a patch of bare rock (a hard substrate)
   • worms burrowing into mud or other sediment (a soft substrate).

From the BioTech Dictionary at http://biotech.icmb.utexas.edu/. For further information see the BioTech homenode.

Sub"strate (?), n.

A substratum.

© Webster 1913.

Sub"strate, a.

Having very slight furrows.

© Webster 1913.

Sub*strate" (?), v. t. [L. substratus, p.p. of substrahere. See Substratum.]

To strew or lay under anything.

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

© Webster 1913.