(transitive, obsolete) To make calm or still; make quiet; calm.
(transitive, nautical) To deprive (a ship) of wind, so that it cannot move (usually in passive).
1555, Richard Eden (translator), The decades of the newe worlde or west India conteynyng the nauigations and conquestes of the Spanyardes by Peter Martyr d’Anghiera, London: Edward Sutton, “The seconde v[o]yage to Guinea,” p. 351,
[…] there we were becalmed the .xx. day of Nouember from .vi. of the clocke in the mornynge vntyll foure of the clocke at after none.