Where does “pigtråd” come from?

pigtråd (Danish) comes from Danish tråd, from Old Danish thraath, from Old Norse þráðr, from Proto-Germanic þrēduz, from Proto-Indo-European treh₁-tu-, from Proto-Indo-European terh₁- — to rub, turn; to drill, pierce.

pigtråd (Danish): barbed wire

Definitions

barbed wire

Ancestry of “pigtråd”, step by step

pigtråd traces back through two separate lines of ancestry.

via Danish tråd

Step	Language	Word	Meaning
1	Danish	tråd	thread; wire; string
2	Old Danish	thraath	—
3	Old Norse	þráðr	thread; past participle of þreyja; past...
4	Proto-Germanic	þrēduz	thread, twisted fibre
5	Proto-Indo-European	treh₁-tu-	—
6	Proto-Indo-European	terh₁-	to rub, turn; to drill, pierce

via Danish pig

Step	Language	Word	Meaning
1	Danish	pig	spike; barb; spine, quill
2	Old Norse	pík	—
3	Proto-Germanic	pīkaz	sharp point, pike, pickaxe, peak

Every word from Proto-Indo-European terh₁- →Every word from Proto-Indo-European treh₁-tu- →Every word from Proto-Germanic þrēduz →