Slacks vs. Trousers

Slacksnoun

(dated) Semi-formal trousers that are less formal than those part of a suit but suitable for wearing in most offices and therefore nowadays no longer considered casual trousers. (Takes a plural verb even when referring to a single pair; may be referred to as a pair of slacks)

Slacksnoun

(usually in the plural) pants for casual wear

Trousersnoun

An article of clothing that covers the part of the body between the waist and the ankles or knees, and is divided into a separate part for each leg.

Trousers

A garment worn by men and boys, extending from the waist to the knee or to the ankle, and covering each leg separately.

Trousersnoun

(usually in the plural) a garment extending from the waist to the knee or ankle, covering each leg separately;

Trousers

Trousers (British English), slacks, or pants are an item of clothing that might have originated in Central Asia, worn from the waist to the ankles, covering both legs separately (rather than with cloth extending across both legs as in robes, skirts, and dresses). In the United Kingdom, the word pants generally means underwear and not trousers.