Origin and history of fold

Middle English folden, "bend, bow down," from Old English faldan (Mercian), fealdan (West Saxon), transitive, "to bend (cloth) back over itself, wrap up, furl," class VII strong verb (past tense feold, past participle fealden), from Proto-Germanic *falthan, *faldan (source also of Middle Dutch vouden, Dutch vouwen, Old Norse falda, Middle Low German volden, Old High German faldan, German falten, Gothic falþan), according to Watkins from PIE *pol-to-, suffixed form of root *pel- (2) "to fold."

Of the arms, from late Old English. The intransitive sense, "become doubled upon itself," is from c. 1300 (of the body); earlier "give way, fail" (mid-13c.). The sense of "to yield to pressure" is from late 14c. The weak conjugation developed from 15c. Related: Folded; folding. Folding-table is attested by late 14c.

"pen or enclosure for sheep or other domestic animals," Old English falæd, falud "stall, stable, cattle-pen," a general Germanic word (cognates: East Frisian folt "enclosure, dunghill," Dutch vaalt "dunghill," Danish fold "pen for sheep"), of uncertain origin. Figurative use by mid-14c.

"a bend or ply in anything," mid-13c., from fold (v.). Compare similarly formed Middle Dutch voude, Dutch vouw, Old High German falt, German Falte, Old Norse faldr.