the act of decreasing or reducing something
"The manager announced a decrease in staff hours starting next Monday to cut costs during the slow season."
An amount by which a quantity is decreased.
"The decrease from last month's sales was surprisingly small despite the market downturn."
In plain English: A decrease is a noun used to describe an amount that has gone down or become smaller.
"The decrease in temperature made everyone want to put on sweaters."
Usage: Use "decrease" as a noun to refer to the specific amount by which something has gone down, such as saying there was a decrease in temperature. It functions grammatically like other countable quantities and can take modifiers like "a large" or "significant."
Of a quantity, to become smaller.
"The number of wildflowers began to decrease after the drought lasted for three months."
In plain English: To decrease means to make something smaller or less.
"The number of customers decreased after the store changed its hours."
Usage: Use decrease as a transitive or intransitive verb to indicate that something becomes smaller in amount, size, or intensity over time. You can say the number decreased without an object or decrease the budget when specifying what is getting smaller.
The word decrease entered English from the Old French descreistre, which originally meant to grow less or diminish. It ultimately traces its roots back to the Latin verb decrescere.