Definition of "oscillation"

The trial running tests which were made with the vehicles showed that they ride very steadily laterally, with almost complete absence of oscillation at all speeds.

1950 January, “British Railways Double-Deck Suburban Stock”, in Modern Railways, page 57

In the early days troubles were experienced with oscillation from the rod drive and with the transformers, but were overcome later, and these machines performed useful service until superseded by more modern locomotives less costly in maintenance.

1960 December, Cecil J. Allen, “Operating a mountain main line: the Bern-Lötschberg-Simplon: Part One”, in Trains Illustrated, page 743

The oscillations were getting so severe that painters on the bridge learned to tie down their tins before a train passed. They found holes and rents in the iron but never reported them as they were never asked, and it wasn't their job. These were deferential times, and few wanted to talk out of turn.

2020 September 23, Paul Bigland, “The tragic tale of the Tay Bridge disaster”, in Rail, page 81