decrement

Even if you've never seen "decrement" before, you might be familiar with "increment," a word for the action or process of increasing or for something that is gained or added. "Increment" arrived in English, after a rather circuitous route involving Anglo-French, from the Latin verb increscere, meaning "to increase." So it should come as no surprise that decrement derives from the Latin verb decrescere, meaning "to decrease." Both words can be traced further back to the verb "crescere," which means "to grow." Like "increment," "decrement" can also have the (much rarer) mathematical sense of "a change in the value of one or more of a set of variables," but "increment" is used for both positive and negative changes, and "decrement" only for negative ones.