Webster's Revised Unabridged Dictionary · 1913

Unmoor

Unmoor , transitive verb

[1st pref. un- + moor.]

(a)
(Nautical) To cause to ride with one anchor less than before, after having been moored by two or more anchors.
(b)
(Nautical) To loose from anchorage. See Moor, transitive verb

Unmoor , intransitive verb

To weigh anchor. — Sir W. Scott