Γνωστός = Οικείος
I just added it, thank you for your comment! ^.^
But seems it still shows it as an incorrect word
ακόμα λάθος το βγάζει το γνωστός-ή
Just from the sound of the name, it's not a surprise that IKEA is popular in Greece, it sounds truly "familiar"...
When I was little, I thought that IKEA was a Greek company because it reminded me of οικία, a more formal way to say house. (οικία has the same root as οικείος, of course).