erratic

Universal Words adjective (often disapproving) not happening at regular times; not following any plan or regular pattern; that you cannot rely on SYNUNPREDICTABLE: The electricity supply here is quite erratic. * She had learnt to live with his sudden changes of mood and erratic behaviour. * Mary is a gifted but erratic player (= she does not always play well). * Irrigation measures will be necessary in areas of erratic rainfall. erratically adverb: He was obviously upset and was driving erratically. * His heart beat erratically.