SEPTENNIUM Meaning of SEPTENNIUM in English [ sɛp'tɛnɪəm ]■ noun ( plural septennia -nɪə or ~s ) rare a period of seven years.OriginC19: from L. septem 'seven' + annus 'year'. Concise Oxford English vocab. Сжатый оксфордский словарь английского языка. 2004