крепостные крестьяне - serfs. https://ru.wikipedia.org/wiki/Крепостное_право realted terms: крепостничество (крепостное право) -serfdom крепость (крепостная зависимость). закрепостить/закрепощать, раскрепостить/щать, прикерпить к земле. Закрепощённый раскрпощённый (cf. very common modern figurative meaning of this: free/liberated, about ones behaviour). This is Much important aspect of our history. Our history was different from Western European one in this respect. Peasants were gradually loosing their rights after Middle Ages, and during 18 century, after Peter the Great reformed and strenghtened the state (in the sense 'state apparatus') the process went expecially fast, and by the end of the century turned into complete nighmare and slavery. Much discussed (at history lessons) question about Catherine the Great is 'why it happened that way that she opposed serfdom on words, but it is during her reign slavery peaked'. If I remember correctly, at the end of 18 century 90% of population were serfs, and yet another 5% free peasants. We are/were a peasant country. So most of Russians you talk with have 'крепостные' as their ancestors. It was abolished in 1861.

Крепостной - the word mean, that person is like a slave but not exactly. In old time there was a master who had a land and a big house, and all men who was living on his land was his 'крепостной'. So 'крепостной прадет' has not any mind. Better to say : мой прадед был крепостным - it mean that your grand grand father was a 'slave'.

Крепостной - people belonging to the fortress / who was the property owner Прадед - great grandfather