The beating down of standing corn by wind or storm. The word is derived from the Latin calamus (a stalk of corn). Hence, Cicero calls a storm Calamitoʹsa tempestas (a corn-levelling tempest).
“Another ill accident is drought, and the spoiling of the corn; inasmuch as the word ‘calamityʹ was first derived from calamus (stalk), when the corn could not get out of the ear.”—Bacon.