1) A short, close-fitting garment which could be worn by both men and women.
1391 Item eidem unum jak defencionis, opertum nigro velveto, Sutton in Holderness
1423 Et de xxs receptis pro j jake deffence de chamlet rubea, cum iij legulis deauratis , York. More usually it was a sleeveless tunic worn by soldiers, made of quilted leather and it may later have been plated with iron: 1450 ‘Also I leave to William Yate 1 tunic called the jake ’, Bradford
1476 lego Ricardo filio meo ... j Jak, j sallet , Aberford
1481 all the money paid for the standerd, javelien, harnesse, jakks ... shalbe born of the Chambre, York
1526 to Gilbert Milner my jake , Halifax
1541 my swerde and buckler, jake and sallet, with all other my fensible aray, Beeston .
2) A measure, half or quarter of a pint (Halliwell).
1720 a pint of dub, a jack of dub, West Riding
1741 betwixt a Jack and a Gill of good Brandy , Pontefract. In some contexts it referred to a drinking vessel, probably short for black jack: 1612 The Buttrie: ... 2 drinking glasses 2 jackes 3 canns
1622 2 black jacks 3s, 12 stond bottells 4s 8d, Brandsby.
3) A machine for turning the spit in roasting meat, first noted in 1587 (OED).
1619 one fire shovel, one poyte and a jacke , Pudsey
1674 Tenn spits a Jack Two pare of racks , Doncaster. Note: 1653 paid to the jack keeper his whole yeare waidges , Stockeld: this servant was responsible also for ‘keeping’ the clock.