Where does “trefnus” come from?

trefnus (Welsh) comes from Welsh -us, from Middle Welsh -us, from Latin -osus, from Old Latin -osos, from Latin ont-to-s, from Latin -o-wont-to-s.

trefnus (Welsh): orderly, tidy, neat

Definitions

Step	Language	Word	Meaning
1	Welsh	-us	adjectival suffix often indicating a...
2	Middle Welsh	-us	-ous, full of, prone to
3	Latin	-osus	-ose, -ous; full of, overly, prone to
4	Old Latin	-osos	accusative masculine plural of -ōsus
5	Latin	ont-to-s	—
6	Latin	-o-wont-to-s	—