In Australia, colloquially, people will use the word 'crystal' to describe cut glass with some lead content. Antique dealers extend that to all glass with some lead content.
There's mention of definitions of 'crystal' and 'semi-crystal' in some of the Tariff Board deliberations from the 1930s, but I can't recall the exact details, being no pedant

. Will try to remember to look it up! (In 1936, there was a quite a fight over importing crystal blanks for cutting. A group called Aura Crystal imported mostly Kosta blanks of 'semi-crystal' for cutting, but were whacked with massive tariffs at the behest of the Australian Glass Manufacturers Co Ltd. Crown Crystal had promised them a batch of test blanks back in the early 30s, then kept making excuses. The batch never appeared, of course.)
Flint glass also is used to mean glass with lead content; however, the Crown Crystal catalogues have 'flint' to describe the colour of clear pressed glass which apparently has no lead content. Crown, of the Australian Glass Manufacturers group, held a monopoly in Australian pressed glass over much of the 20th Century.
Strangest of all, some people (including my grandmother) call pressed glass 'crystal', and colourless glass 'white'. :huh: