twinsets

Noun

twinset (plural twinsets)

1. A combination of a cardigan and a jumper, usually knitted in wool or cashmere.
   • She was dressed to receive, as her mother would have said, and she had been standing at the window in her blue twinset for an hour, waiting for the car, waiting for the doorbell, waiting for the soft turn of her husband's key in the latch.1986, John le Carré, A Perfect Spy
2. A pair of cars or locomotives that are permanently coupled and treated as a single unit.
3. 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, John Bantin, Amazing Diving Stories