Webster's Revised Unabridged Dictionary · 1913

Decrease

Decrease , intransitive verb

[Old English decrecen, from Old French decreistre, French décroître, or from the Old French noun (see Decrease, n.), from Latin decrescere to grow less; de + crescere to grow. See Crescent, and compare Increase.]

To grow less, -- opposed to increase; to be diminished gradually, in size, degree, number, duration, etc., or in strength, quality, or excellence; as, they days decrease in length from June to December.
He must increase, but I must decrease. — John iii. 30
The olive leaf, which certainly them told The flood decreased. — Drayton
Crete's ample fields diminish to our eye; Before the Boreal blasts the vessels fly. — Pope

Decrease , transitive verb

To cause to grow less; to diminish gradually; as, extravagance decreases one's means.
That might decrease their present store. — Prior

Decrease , noun

[Old English decrees, Old French decreis, from decreistre. See Decrease, v.]

1.
A becoming less; gradual diminution; decay; as, a decrease of revenue or of strength.
2.
The wane of the moon. — Bacon