1. An intensifier used when one puts forth great effort to do something. I'm planning to fight like hell against this illness, so I'm researching both Western and Eastern methods of treatment.
2. A phrase used to convey one's impassioned denial, refusal, or rejection of something. A: "I don't care what you say, Mom—I'm going to that party!" B: "Like hell you are!"
exclam. That is not true!; I do not believe you! (Use caution with hell.) You’re going to a Dead concert! Like hell!
See also: like