twinset

noun3

1. •
   A combination of a cardigan and a jumper, usually knitted in wool or cashmere.

   • I need these people, the Sergeant, and Mr. Tighe the shopman in the village, even Miss Broaders, she of the pink twinsets and tight mouth, who presides over the post office. — 1993
2. •
   A pair of cylinders containing air for the diver to breathe.

   • Tim and Rob both went into the water each armed with a twinset of air and a sling-tank of 50 per cent oxygen for use in decompression. — 2012
3. •
   A pair of cars or locomotives that are permanently coupled and treated as a single unit.