forty

The word "forty" originates from Old English "fēowertig," which is a compound of "fēower" (four) and "tig" (a group of ten). This structure is common in the Germanic numbering system, where multiples of ten are formed by combining the unit number with a suffix denoting a decade. The spelling evolution from "four" to "for-" in "forty" reflects a Middle English phonetic shortening, distinct from the preserved "u" in "four" itself. Thus, "forty" represents a fused and phonetically streamlined descendant of the ancient Germanic decimal construction.

This is a simplex word derived from Old English. Its spelling and form have evolved as a single lexical unit.