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 (of the body or limbs); earlier "give way, fail" (mid-13c.). Sense of "to yield to pressure" is from late 14c. Related: Folded ; folding .