1) A contraction of ‘two winter’, used of animals such as sheep and cattle which were two winters old.
1362 ‘5 bullocks called Tuynters’, Mitton
1446-58 xvj Twynters et sterkes, Fountains Abbey
1541 my twynters, that is to say, ij quyes and ij stottes, Otley. It was applied adjectivally in compounds: 1442 septem animalia vocata twynternawt, Rylstone
1545 Item 11 twenter neytte, Ł4 8s, Muker
1619 twinter stages, twinter beastes.