"A serious man"
Translation:En alvorlig mann
No, I think these are false friends.
Bokmålsordboka defines "seriøs" thusly: som fortjener å bli tatt alvorlig, som er alvorlig ment ("which deserves to be taken seriously, which is meant in earnest").
"Firmaet er meget seriøst" -> "The firm is very reliable" "En seriøs artist" -> "An earnest/bona fide artist"
Although many Norwegians would translate "Seriously!?" as "Seriøst?!" - so I guess we could be looking at a shift in meaning. A better traslation would be "Mener du det alvorlig?" which doesn't really roll of the tongue...