unpredictable adjective 1noun 1forms 3 adjective1 •Unable to be predicted.Sharks are not unpredictable; for the most part, they do exactly what an apex predator is expected to do. — 1983 noun1 •An unpredictable thing.Other unpredictables, like the recent unexpected blizzards and those of 2 years ago, or a hurricane can cost us many thousands of dollars, and have a severe impact on equipment and facilities. — 1960 formsunpredictables · more unpredictable · most unpredictable