The Collaborative International Dictionary of English v.0.48:
Mortgage \Mort"gage\ (m[^o]r"g[asl]j; 48), n. [F. mort-gage;
mort dead (L. mortuus) + gage pledge. See Mortal, and
1. (Law) A conveyance of property, upon condition, as
security for the payment of a debt or the preformance of a
duty, and to become void upon payment or performance
according to the stipulated terms; also, the written
instrument by which the conveyance is made.
Note: It was called a mortgage (or dead pledge) because,
whatever profit it might yield, it did not thereby
redeem itself, but became lost or dead to the mortgager
upon breach of the condition. But in equity a right of
redemption is an inseparable incident of a mortgage
until the mortgager is debarred by his own laches, or
by judicial decree. --Cowell. --Kent.
2. State of being pledged; as, lands given in mortgage.
Chattel mortgage. See under Chattel.
To foreclose a mortgage. See under Foreclose.
Mortgage deed (Law), a deed given by way of mortgage.