Vierfach

Vierfach is a German adjective and adverb meaning fourfold or quadruple. It describes something multiplied by four or occurring four times as often, and can modify nouns or be used with adjectives and verbs to express multiplicative relations.

Grammatically, vierfach is used attributively before a noun as a modifier: eine vierfache Steigerung; with a definite article: die vierfache Steigerung der Leistung. The noun form is das Vierfache. In predicative constructions it can be used with sein: Der Wert ist vierfach größer; and as an adverbial modifier: Die Kosten sind vierfach gestiegen. Many speakers also use the variant viermal so groß to express the sense of four times as large.

Etymology and related forms: Vierfach is formed from vier plus the suffix -fach, which denotes a multiplicative factor. It belongs to a family including zweifach, dreifach, fünffach. The word vielfach exists as well, meaning many times or in many cases.

Usage notes: In technical, scientific or mathematical writing vierfach conveys a precise factor of four. In everyday language, speakers often prefer viermal or the noun form Das Vierfache to avoid confusion.