Definition of "unauthorised"

A dozen similar, but smaller footwarmers were made at Doncaster, without official sanction, and placed in the coaches of a train conveying some of the directors to London. Sturrock was taken to task by the chairman for having incurred this unauthorised expenditure, but before he left the meeting, the directors had ordered 200 footwarmers for public use.

1948 January and February, “Memoirs of Archibald Sturrock”, in Railway Magazine, page 47

[...] the fence provided by NR was substandard and poorly maintained, such that unauthorised access to the railway was straightforward.

2021 January 13, “Network News: NR fined after teenage trespasser suffers electrocution injuries”, in RAIL, issue 922, page 17