The Collaborative International Dictionary of English v.0.48:

Escrow \Es"crow\, n. [OF. escroe, escroue, a roll of writings,
   bond. See Scroll.] (Law)
   A deed, bond, or other written engagement, delivered to a
   third person, to be held by him till some act is done or some
   condition is performed, and then to be by him delivered to
   the grantee. --Blackstone.
   [1913 Webster]

WordNet (r) 3.0 (2006):

escrow
    n 1: a written agreement (or property or money) delivered to a
         third party or put in trust by one party to a contract to
         be returned after fulfillment of some condition

The Free On-line Dictionary of Computing (19 January 2023):

escrow

    An arrangement where something (generally money or
   documents) is held in trust ("in escrow") by a trusted third
   party until certain agreed conditions are met.  In computing
   the term is used for key escrow and also for source code
   escrow.

   (1999-12-14)