1) Either a loom for weaving the woollen 'Bastard' cloth or a loom irregular in some respect.
In 1498, the Beverley weaver Robert Dacres left to his friend John Williamson unum bastard-lome and to his apprentice another bastard-lome. Both the looms were dual purpose, the apprentice’s for example had iiij heyldes et sleys pro panno lineo et iiij pro panno canabeo. The name may be connected with the weaving of woolen cloths called Basterds in an Act of 1483 and again with White brode woollen clothes with Crumpil listes, otherwise called bastardes in 1523. Alternatively, the loom may have been irregular in certain respects. Online references indicate that the term was still in use in the 1980s.