overvast UK /əʊvəbɜːst/US /ˈəʊvəbɝst/ adjective1 •(rare) Overly vast.The first two days of the camp were slightly overvast and 1 windy, but the remaining period was true autumn weather, which allowed full advantage to be taken of our open-air holidays. — 1905 formsmore overvast · most overvast