Unpredictable refers to something or someone that is not able to be predicted or foreseen. Erratic, fitful, variable, ā¦ How to use unpredictable in a sentence. Something that is unpredictable: He is utterly unpredictable. Not to be foreseen or foretold. Unā²preā¢dictā²aā¢bilā²iā¢ty, unā²preā¢dictā²aā¢bleā¢ness, n. Changing a lot so it is impossible to kn. : See examples of unpredictable used in a sentence. If you describe someone or something as unpredictable, you mean that you cannot tell what they are going to do or how they are going to behave. The meaning of unpredictable is not predictable. Likely to change suddenly and without reason and therefore not able to be predicted (= expectedā¦. How common is the word unpredictable? The unpredictable weather in the mountains can make climbing extremely hazardous. The unpredictables of life. Something that is unpredictable. Unpredictable meaning, definition, what is unpredictable: That cannot be predicted because it changes a lot or depends on too many different things. See āmeaning & useā for definitions, usage, and quotation evidence. Not to be foreseen or foretold: There are two meanings listed in oeds entry for the word unpredictable. It generally applies to circumstances, situations, events, or behaviors that change so often or are ā¦ Variable, uncertain, or erratic. An unpredictable occurrence.