These words mean to make or to become smaller or less, but they are not in all cases interchangeable. Reduce has a wider range of connotations than the other words and is also the most general. It means to make less in size, amount, number, extent or intensity: to reduce household expenses; to reduce a labour force during a slack season; to reduce speed on a highway undergoing repairs; to reduce the acreage of a property by selling off several paddocks. Reduce further means to bring to an inferior rank, position or financial condition: a widow reduced to letting rooms to make ends meet: a sergeant reduced to private after a court-martial; a pampered woman reduced to doing her own housework because of a shortage of domestic help. When applied to losing weight, especially when deliberate, reduce is popularly used intransitively: My mother and aunts are always trying new diets in order to reduce .

Abate means to reduce , as in strength or degree, usually from an excessive intensity or amount. In this sense, it is most frequently an intransitive verb.

• The anguished screams in the night began to abate when the police arrived; After taking aspirin, she found her pain abating .

In a legal sense, abate is used transitively and means to do away with completely or to make null and void in whole or in part: to abate a nuisance; to abate rent.

Curtail is to reduce abruptly and radically, as by cutting off or cutting shorter than was originally intended. The word is used chiefly of nonmaterial things and conveys the idea of the unexpected: a holiday curtailed by a gale-force wind that damaged their cottage; to curtail a pointless argument by turning on one’s heel and leaving the room; to curtail useless government spending.

Diminish is a more accurate word than reduce when one wishes to stress the idea of removing part of something so that there is a manifest and sometimes progressive lessening, but not to the point of total disappearance. The word may suggest either the loss of something valuable or a lessening of that which is undesirable.

• As people approach old age their energy may diminish ; As his confidence in his work increased, his anxieties about it diminished .

Lower is to make less, especially in value, degree or level. It is not as emphatic or precise a word as reduce in this sense, although fairly close in meaning: to lower prices on shop-soiled goods; to reduce payments on a mortgage. In extended senses, lower points to a lessening by undermining or weakening.

• He could not bear to lower himself to ask relatives for help; Frequent colds lower one’s resistance to more serious infections.