To pledge; to give as a pledge for the performance of some act; as, to plight faith, honor, word; -- never applied to property or goods.
To promise; to engage; to betroth.
a solemn pledge of fidelity
promise solemnly and formally; "I pledge that will honor my wife"
Plight, an homonymous word now used chiefly with two meanings, (1) pledge, and (2) condition or state. The first appears more generally in the verbal form, to plight one's troth, and the second with a direct or imagined sense of misfortune. The derivations of the two words show they are quite distinct in origin.