erratic /ɪˈɹætɪk/adjective 2noun 2forms 3 adjective2 •Unsteady, random; prone to unexpected changes; not consistent.Henry has been getting erratic scores on his tests: 40% last week, but 98% this week.When we found you on the street, your behavior was all erratic and it seemed like you were having a panic attack. •Deviating from normal opinions or actions; eccentric; odd. noun2 •A rock moved from one location to another, usually by a glacier.The term for a displaced boulder is an erratic, but in the nineteenth century the expression seemed to apply more often to the theories than to the rocks. — 2003 •Anything that has erratic characteristics. formserratics · more erratic · most erratic