supervacaneous UK /ˌsuːpəvəˈkeɪnɪəs/US /ˌsuːpəɹvəˈkeɪnɪəs/ adjective1 •(no longer used) Added above what is needed or necessary; superfluous, redundant.It is an awful thing to find your efforts supervacaneous when you are so far away from home and friends, sympathy, and help. — 1915