Where does “lethich” come from?

lethich (Old Frisian) comes from Proto-Germanic liþugaz, from Proto-Germanic -gaz, from Proto-Indo-European -ḱos — -y, -ic.

Ancestry of “lethich”, step by step

StepLanguageWordMeaning
1Proto-Germanicliþugazflexible, free, unoccupied
2Proto-Germanic-gaz-y
3Proto-Indo-European-ḱos-y, -ic
Every word from Proto-Indo-European -ḱos →Every word from Proto-Germanic -gaz →Every word from Proto-Germanic liþugaz →