It negates the Shock spell's effect and is negated by the Choke spell's effect. Rasp, Drown, and Frost are a family of compatible effects that can all stack together. Burn and Rasp also stack.
Rasp is an English verb meaning is to scrape or file down. Since many iterations of the spell throughout the series involve damaging a target's MP, or dealing damage over time, this definition is likely the most appropriate.