The story
- Proto-Indo-European*sed-
- Proto-Indo-European*sodéyeti
- Proto-Germanic*satjaną
- Proto-West Germanic*sattjan
- Old Englishsettan
- Middle Englishsetten
- Middle Englishsettere
- English todaysetter
From Middle English settere, equivalent to set + -er. Compare West Frisian setter, Dutch zetter, German Low German Setter, German Setzer. The hunting dogs are so named because when they scent the game, they set (that is, strike a certain stance).
Etymology from Wiktionary, CC BY-SA 4.0.