1) An apprentice was said to be 'loose' once he had completed his term.
1539 I dyd lowsse John my sonne furthe his apprentyschippe which was no lytill coste, Pannal
1552 To Barnard Spinke ... when he ys loyse of his prentishipe xxs , Featherstone
1690 Peeter Dawson hired June the 16th for 25s & to be lowse at whitsun, Conistone. This probably explains what a loose suit was - not a loose-fitting garment. In 1778, John Haste [Hayhurst] of Tong was bound apprentice to Samuel Pitchforth of Elland with consent of his mother: in the final part of the agreement was a requirement that in due Season the said Master would finde all Aparil or Cloaths which is Nesesary … that is one sute for work days and one for Holydays and one Loose sute at the end of the time.