(slang) fuck; sometimes a combination of "fuck" and "hell". The word has both senses of the word 'fuck', as is exemplified in the episode 'Meltdown', when, while John and Aeryn are getting frisky, a bang is heard, followed by the following short conversation: "Frell." "Yeah." "No, bad frell."
Expletive which means F**K (e.g. "Frell you" or "Get the Frell away from there").