septennial

SEPTENNIAL

septennis (Plaut.); septem annorum: septimo quoque anno factus (or other suitable participle of what is done every seven years).

septennial: perh. septuennis or septennis (which, however is found only in the sense of seven years old: cf. triennis, triennia); or expr. by circuml., *(dies) qui septimo quoque anno revertitur: *(sacrum) quod septimo quoque anno fit, celebratur.