Where does “realfag” come from?

realfag (Norwegian Bokmål) comes from Norwegian Bokmål real, from Late Latin realis, from Latin rēs, from Latin vindicatio, from Latin vindicō, from Latin vindex, from Latin dīcō, from Latin -tiō — small stone, pebble; gravel, rubble.

realfag (Norwegian Bokmål): mathematics and natural science

Definitions

mathematics and natural science

Ancestry of “realfag”, step by step

realfag traces back through two separate lines of ancestry.

via Norwegian Bokmål real

Step	Language	Word	Meaning
1	Norwegian Bokmål	real	actual, real; the real, monetary unit of Brazil
2	Late Latin	realis	actual; real, actual
3	Latin	rēs	thing, object, stuff
4	Latin	vindicatio	civil lawsuit; protection, defence; vindication;...
5	Latin	vindicō	to lay claim to as one's own (often with sibi)
6	Latin	vindex	claimant, vindicator
7	Latin	dīcō	to say, talk, speak, utter, mention
8	Latin	-tiō	tion, -ation, -ing
9	Latin	dissertātiō	(spoken) dissertation, discourse, disquisition
10	Latin	dissertus	arranged, disposed; explained
11	Latin	disserere	second-person singular future passive indicative...
12	Latin	dis-	asunder, apart, in two; reversal, removal;...
13	Latin	calceus	shoe
14	Latin	calx	limestone; chalk; the finish line
15	Ancient Greek	χάλιξ	small stone, pebble; gravel, rubble

via Norwegian Bokmål fag

Step	Language	Word	Meaning
1	Norwegian Bokmål	fag	a subject; a profession, trade, discipline

Every word from Ancient Greek χάλιξ →Every word from Latin -tiō →Every word from Latin dis- →