Untie, v. t.
Etymology: [AS. unt. See 1st Un-, and Tie, v. t.]
1. To loosen, as something interlaced or knotted; to disengage the parts of; as, to untie a knot. Sacharissa's captive fain Would untie his iron chain. Waller. Her snakes untied, sulphurous waters drink. Pope.
2. To free from fastening or from restraint; to let loose; to unbind. Though you untie the winds, and let them fight Against the churches. Shak. All the evils of an untied tongue we put upon the accounts of drunkenness. Jer. Taylor.
3. To resolve; to unfold; to clear. They quicken sloth, perplexities untie. Denham.
1 other Webster entry under this spelling
Untie, v. i.
To become untied or loosed.
Shades of meaning
Fernald lists untie only as an antonym, under bind.
He lists it without comment; the entries above explain its neighbors.