mensiversary UK /ˌmɛnsɪˈvɜːs(ə)ɹi/US /ˌmɛnsɪˈvɝs(ə)ɹi/ noun1 •(rare) A day that marks an exact month (or specified number of months) since the occurrence of a significant event.How flourishes the King of Clubs? I always observe its mensiversary in my fancy. — 1805 formsmensiversaries