v the wane of the moon.
2. decrease ·v a becoming less; gradual diminution; decay; as, a decrease of revenue or of strength.
3. decrease ·vt to cause to grow less; to diminish gradually; as, extravagance decreases one's means.
4. decrease ·noun 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.