Vermifuge comes from New Latin vermifuga and vermifugus. Vermi- contains Latin vermis. The -fuge ending traces to fugare, to put to flight. The modern word covers agents that expel or destroy parasitic worms.
Fugare is the causing-to-flee verb; the puzzle does not gloss it simply as flee.
Sources
- Merriam-Webster: vermifuge
The word comes from the New Latin formations and denotes expelling or destroying parasitic worms.
- Merriam-Webster: vermi-
Latin vermis means worm.
- Merriam-Webster: -fuge
The ending traces to Latin fugare, to put to flight.
- Online Etymology Dictionary: vermi-
Also built on Latin *vermis* "worm": vermin, vermicelli
- Online Etymology Dictionary · vermifuge
Meanings of the older forms on the word path.