From Wiktionary, the free dictionary
From un- + hittable.
unhittable (not comparable)
- Impossible to hit
2007 October 21, Jack Curry, “Unlikely Star Helps Red Sox Force Deciding Game”, in New York Times[1]:Carmona flashed an unhittable pitch as he struck out Ramirez with a 96-mile-an-hour fastball that dived under Ramirez’s hands.
