Where does “trælle” come from?

trælle (Danish) comes from Old Danish trælæ, from Old Norse þræla, from Old Norse þræll, from Proto-Germanic þragilaz, from Proto-Indo-European trāgʰ- — pull, drag, race, run; to pull, drag, race, run.

trælle (Danish): to slave, toil as a slave; indefinite plural of...

Definitions

to slave, toil as a slave; indefinite plural of...

Ancestry of “trælle”, step by step

Step	Language	Word	Meaning
1	Old Danish	trælæ	—
2	Old Norse	þræla	to call a thrall
3	Old Norse	þræll	slave
4	Proto-Germanic	þragilaz	runner; gofer; servant
5	Proto-Indo-European	trāgʰ-	pull, drag, race, run; to pull, drag, race, run

Every word from Proto-Indo-European trāgʰ- →Every word from Proto-Germanic þragilaz →Every word from Old Norse þræll →