Old English faldan (Mercian), fealdan (West Saxon), transitive, "to bend cloth back over itself," class VII strong verb (past tense feold, past participle fealden), from Proto-Germanic *falthan, *faldan (cf. Middle Dutch vouden, Dutch vouwen, Old Norse falda, Middle Low German volden, Old High German faldan, German falten, Gothic falþan).
The Germanic words are from PIE *pel-to- (cf. Sanskrit putah "fold, pocket," Albanian pale "fold," Middle Irish alt "a joint," Lithuanian pleta "I plait"), from root *pel- (3) "to fold" (cf. Greek ploos "fold," Latin -plus).
The weak form developed from 15c. In late Old English also of the arms. Intransitive sense, "become folded" is from c.1300 (of the body or limbs); earlier "give way, fail" (mid-13c.). Sense of "to yield to pressure" is from late 14c. Related: Folded; folding.
"pen or enclosure for sheep or other domestic animals," Old English falæd, falud "stall, stable, cattle-pen," a general Germanic word (cf. 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.).
fold 1 (fōld)
A crease or ridge apparently formed by folding, as of a membrane; a plica.
In the embryo, a transient elevation or reduplication of tissue in the form of a lamina.
an enclosure for flocks to rest together (Isa. 13:20). Sheep-folds are mentioned Num. 32:16, 24, 36; 2 Sam. 7:8; Zeph. 2:6; John 10:1, etc. It was prophesied of the cities of Ammon (Ezek. 25:5), Aroer (Isa. 17:2), and Judaea, that they would be folds or couching-places for flocks. "Among the pots," of the Authorized Version (Ps. 68:13), is rightly in the Revised Version, "among the sheepfolds."