The story
After Ronald Fintushel and Ronald J. Stern, seemingly because of their 1980 paper "Constructing Lens Spaces by Surgery on Knots".
Etymology from Wiktionary, CC BY-SA 4.0.
Fintushel-Stern knot
Today it means: The three-tangle pretzel knot with two right-handed twists in its first tangle, three left-handed ones in its second, and seven left-handed ones in its third. Full definition →