Definition of "unusable"

From that night until mid-morning on Sunday, November 6, the station was unusable by any electric trains and the Brighton-Eastbourne service was maintained by steam traction, assisted by two Hastings six-car diesel muliple-units—[...].

1961 January, “Talking of Trains: Flooding at Lewes”, in Trains Illustrated, page 5

This service has suffered badly from Department for Transport-inspired cuts which reduced it from hourly to two-hourly. This, coupled with regular cancellations, has rendered the train service between the area's two biggest towns almost unusable.

2022 November 2, Paul Bigland, “New trains, old trains, and splendid scenery”, in RAIL, number 969, page 57

All the fat, skin, bones and unusables from the slaughter house went to the soap factory, and got diverted to feed a company of soldiers.

2004, Frank Kolondra, Never a Straight Path, page 176