To spin-dry clothes is to get most of the water out of them by whirling them around very fast, so that the water is thrown out through holes in the drum. It is not heat drying — nothing gets warm, and the clothes come out damp, not dry. They still need to hang on the line or go into a tumble dryer afterwards.

This is a verb: you spin-dry a shirt, the machine spin-dries the load, the towels were spun-dried. Note the past form follows 'spin': spun. It first appeared in print in the 1920s, when washing machines were new and this was a machine's selling point.

A point about how the word actually lives today. In Taiwan, and in most homes now, washing and spinning happen in the same machine — the spin is just the last stage of a wash cycle. So people talk about 'the spin cycle' or say the machine 'spins' the clothes, and the full verb 'spin-dry' sounds a little old-fashioned or a little technical, the kind of thing you read on a manual or an appliance label. Older speakers, especially in Britain, used it more freely because they remembered a separate machine that did only this job.

The word also has a joking use for people: someone who comes out of a difficult experience shaken and limp is 'wrung out and spun dry'. And be careful of one thing — the entry you may see calls this 'a machine'. That is the noun spin-dryer. The verb is the action.