fasten: [OE] Etymologically, fasten means ‘make fast’; it goes back ultimately to Germanic *fastuz, source of English fast. From this was derived a verb *fastinōjan, which passed into Old English as fæstnian. To begin with this seems only to have been used in the metaphorical sense ‘settle, establish’. The more concrete ‘attach’ is not recorded until the 12th century, and the earliest reference to its use for locking or bolting a door comes from as late as the mid-18th century. => fast
Old English fæstnian "make fast, make firm, fix, secure," also "ratify, betroth, confirm," from Proto-Germanic *fastinon "to make firm or fast" (cognates: Old Frisian festnia "to make firm, bind fast," Old Saxon fastnon, Old High German fastnion, German festnen, Old Norse fastna "to pledge, betroth"), from PIE *fast "solid, firm" (see fast (adj.)). Related: Fastened; fastening.