Ivan IV Tsar of All Russia, Grand Prince of Moscow - crowned the first czar of all Russia.

"In Russia Ivan was called "Grozny", which has always been translated to "the Terrible", but actually means "the Awesome"."

It could be from the word gross, Germanic meaning great.
"great (adj.) Look up great at Dictionary.com
Old English great "big, tall, thick, stout; coarse," from West Germanic *grautaz "coarse, thick" (cognates: Old Saxon grot, Old Frisian grat, Dutch groot, German groß "great"). "

Just want to remind you that you are talking about my 6th Cousin 14 times
removed. So be warned.

Really I had another look. He really is my 6th Cousin 14 times removed. Please have a look. I am not going to be a pretender for the Russian throne.

Charlemagne is my 35 th Great grandfather

Not sure if I'm being pedantic, but wasn't his (and later Tzars) title "Tzar of All the Russias"?

This covered Great Russia, Little Russia (modern Ukraine, roughly) and White Russia (modern Belarus, roughly).

@A.Saarinen Hi,
Some information about our relation to Ivan the Terrible. My grandfather's family was ennobled by Ivan in the second half of the 16th century.

And we (you and I) have the following relationship:
A. Saarinen is your wife's first cousin four times removed's husband's sister's husband's brother's wife's second cousin four times removed.
kind regards
Jan

A. Saarinen oletko tehty dna-testi?