"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...
But serious in English can also mean something like "reliable"... so maybe if you translate from English to Norwegian you can chose either word depending on what context you chose to interpret I guess.