Definition of "slowing"

The Wycombe slowing begins at West Wycombe; to the High Wycombe curve itself most exaggerated respect was shown, with a minimum of 30 m.p.h.

1961 February, Cecil J. Allen, “Locomotive Running Past and Present”, in Trains Illustrated, page 87

We have seen Parkinsonism as sudden starts and stops, as odd speedings and slowings.

1973, Oliver Sacks, Awakenings

While the first part to Manchester is level after the initial climb out of Liverpool, the section over the Pennines between Manchester and Leeds is very difficult, with steep gradients as well as many slowings over junctions and curves.

2021 January 13, David Clough, “Trans-Pennine transport transformers”, in RAIL, issue 922, page 58