Dictionary of Biblical Words:
(See 2 Cor. 5:5.). The pledge or foretaste of all our heavenly blessings. It is the Spirit that is the earnest, and we are indwelt by Him as the earnest of our inheritance until we reach it.
Boyd’s Bible Dictionary:
(pledge). Pledge (Gen. 38:17); surety (Prov. 17:18); hostage (2 Kings 14:14); deposit or advance (2 Cor. 1:22; Eph. 1:14).
Concise Bible Dictionary:
See HOLY SPIRIT.