Polish cossack cavalry

[FierceKitty]

These chaps were known as pancerni Cossacks, meaning that they were armoured Cossacks (cf. Panzer). The word Cossack tended to vanish in response to the great rebellions, though of course this made nonsense of the actual sense, rather as American has mutated the meaning of forensic.

[Kadrinazi]

Not so much, term 'pancerni' for large part of second half of 17th century was used only to mark better equipped units or those of higher status (i.e. hetman's), while rest of such cavalry was still called 'jazda kozacka' (cossacks, not Cossacks). During 1672-1676 war with Ottomans term 'pancerni' started to be used for all 'jazda kozacka', no matter what equipment and armour they had. Despite this, there are still some period sources, including army musters, that use older term 'jazda kozacka' or 'kozacy', without bothering with name 'pancerni'.