stretchyoudaoicibaDictYouDict[stretch 词源字典]
stretch: [OE] Stretch comes from a prehistoric West Germanic *strakkjan (source also of German strecken and Dutch strekken). This was formed from a base *strak-, which probably also produced English straggle [14]. It is not certain where *strak- came from, but probably it was an alteration of *strak- ‘rigid’ (source of English starch and stark).

Reversal of speech sounds (here a and r) is quite common; the process is known as metathesis. The notions of ‘rigidity’ and ‘stretching’ do not appear very compatible at first sight, but it is thought that the original application of stretch was to ‘stretching the limbs’, in the sense of making them straight or ‘stiff’. Straight comes from a former past participle of stretch.
=> straggle, straight[stretch etymology, stretch origin, 英语词源]
stretch (v.)youdaoicibaDictYouDict
Old English streccan (transitive and intransitive) "to stretch, spread out, prostrate; reach, extend" (past tense strehte, past participle streht), from Proto-Germanic *strakjanan (cognates: Danish strække, Swedish sträcka, Old Frisian strekka, Old High German strecchan, Middle Low German, Middle Dutch, Old High German, German strecken "to stretch, draw out"), perhaps a variant of the root of stark, or else from PIE root *strenk- "tight, narrow; pull tight, twist" (see string (n.)).

Meaning "to extend (the limbs or wings)" is from c. 1200; that of "to lay out for burial" is from early 13c. To stretch one's legs "take a walk" is from c. 1600. Meaning "to lengthen by force" first recorded late 14c.; figurative sense of "to enlarge beyond proper limits, exaggerate," is from 1550s. Stretch limo first attested 1973. Stretch marks is attested from 1960. Related: Stretched; stretching.
stretch (n.)youdaoicibaDictYouDict
late 12c., "expanse of land;" 1540s, "act of stretching," from stretch (v.); meaning "unbroken continuance of some activity" is first recorded 1660s; meaning "straightaway of a race course" (as in home stretch) is recorded from 1839.