Where does “amortering” come from?

amortering (Swedish) comes from Swedish -ing, from Old Swedish -ing, from Old Norse -ing, from Proto-Germanic -ingō — -ing.

amortering (Swedish): amortization the act of reducing a loan principal in installments

Definitions

Step	Language	Word	Meaning
1	Swedish	-ing	Used to form verbal nouns from verbs; -ing. See...
2	Old Swedish	-ing	Forms gerund nouns from verbs
3	Old Norse	-ing	Forms gerund nouns from verbs
4	Proto-Germanic	-ingō	-ing