term:

Earnest

earnest n

[Anglo-French ernes(t) erles, alteration of Old French erres, plural of erre pledge, earnest, alteration of Latin arra, short for arrabo, from Greek arrhabōn, of Semitic origin]
: something of value given by a buyer to a seller to bind a bargain

Source: Merriam-Webster's Dictionary of Law ©1996. Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Incorporated.