Indentation hardness
Hardness measurements quantify the resistance of a material to plastic deformation. Indentation hardness tests compose the majority of processes used to determine material hardness, and can be divided into two classes: "microindentation" and "macroindentation" tests. Microindentation tests typically have forces less than . Hardness, however, cannot be considered to be a fundamental material property. Classical hardness testing usually creates a number which can be used to provide a relative idea of material properties. As such, hardness can only offer a comparative idea of the material's resistance to plastic deformation since different hardness techniques have different scales.
Grit (personality trait)
Salvatore Maddi (2006) defined "hardiness" as a combination of attitudes that provide the courage and motivation to do the hard, strategic work of turning stressful circumstances from potential disasters into growth opportunities. While grit is primarily a measure of an individual's ability to persist in obtaining a specific goal over an extended time period (Duckworth et al., 2007), hardiness refers to an individual's ability to persist through difficult circumstances and does not address the individual's long term persistence toward a specific goal. Maddi (2006) developed a theoretical model of hardiness as a tool for developing resilience.