/ ɪˈrætɪk; NAmE / adjective , noun
■ adjective
(often disapproving ) not happening at regular times; not following any plan or regular pattern; that you cannot rely on
SYN unpredictable :
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) .
► er·rat·ic·al·ly / -kli; NAmE / adverb :
He was obviously upset and was driving erratically.
■ noun
(also erˌratic ˈblock , erˌratic ˈboulder ) ( geology ) a large rock that is different from the rock around and was left behind when a large mass of ice melted
••
WORD ORIGIN
late Middle English : from Old French erratique , from Latin erraticus , from errare to stray, err.