Grit
Part of speech: verb
Definition: To clench, particularly in reaction to pain or anger; apparently only appears in gritting one's teeth. To cover with grit.
Part of speech: noun
Definition: Collection of hard small materials, such as dirt, ground stone, debris from sandblasting or other such grinding, swarf from metalworking. Inedible particles in food. A character trait that means to have courage, fearlessness, or guts. Husked but unground oats.
Gumption
Part of speech: noun
Definition: Energy of mind and body, enthusiasm.Boldness of enterprise; initiative or aggressiveness, guts; spunk; initiative.