The Collaborative International Dictionary of English v.0.48:

freeze-dried \freeze-dried\ adj.
   dried by freezing and applying a vacuum; -- used of tissue or
   blood or serum or other biological substances.

   Note: This technique is gentler than other drying techniques
         and caused less damage or deterioration to sensitive
         substances. It is used primarily as a method to
         preserve foods or substances, and permit storage
         without deterioration.

   Syn: lyophilized, lyophilised.
        [WordNet 1.5 +PJC]

The Collaborative International Dictionary of English v.0.48:

Freeze-dry \Freeze"-dry`\ (fr[=e]z"-dr[imac]`), v. t. [imp. & p.
   p. Freeze-dried; p. pr. & vb. n. Freeze-drying.]
   to remove the moisture from (e.g. food) by first freezing and
   then subjecting to a high vacuum; -- used as a mild method
   for drying foods or chemicals while causing little
   decomposition, in contrast to heat-drying.

   Note: This is a relatively gently drying process used to
         preserve food or sensitive biological materials. For
         biochemical materials, the term lyophilize is often
         used.
         [PJC]

WordNet (r) 3.0 (2006):

freeze-dried
    adj 1: used of tissue or blood or serum or other biological
           substances; dried by freezing in a high vacuum [syn:
           lyophilized, lyophilised, freeze-dried]
    2: preserved by freezing and drying in a vacuum; "freeze-dried
       coffee"