sometimes also "knave" for "Bube"

The Queen of Hearts
She made some tarts
All on a summer's day;
The Knave of Hearts
He stole those tarts
And took them clean away.

The King of Hearts
Call'd for those tarts
And beat the Knave full sore
The Knave of Hearts
Brought back the tarts
And vow'd he'd steal no more.

Charles Lamb (1775 - 1834)

"Knave" is a bit dated, though, don't you think?

"Jack" is definitely the most common word used in cards, but my grandparents still use "knave" and you'd find it in things like Disney or Alice in Wonderland.

"Jack" is definitely the most common word used in cards, but my grandparents still use "knave" and you'd find it in things like Disney or Alice in Wonderland.

That is because a) Disney does a version of "Alice in Wonderland" and b) "Alice in Wonderland" contains the characters from the above-cited poem.

And your grandparents are presumably of the older generation. But the usage could also be regional, of course.