The practice of being sexually or romantically unfaithful.

On two occasions; twice.

(transitive) To be unfaithful to one's (sexual) partner. / (transitive) To double-cross.

(film) A scene shot with the camera positioned to observe two actors.

Alternative spelling of twofold

(US, slang) Twenty-five cents, or a quarter.

In a two-faced manner.

measuring two inches by four inches / (by extension) small or cramped

(construction) A length of lumber having a cross section of two inches by four inches, or in the case of dimensional lumber three and a half inches by one and a half inches.

Consisting of two layers or two strands. / (textile fabrics) Consisting of two webs woven into one another. / (manufactured articles, linen) Consisting of two thicknesses.