TRIWEEKLY

Tri″week′ly (?), a. [[Pref. tri- + weekly.]] Occurring or appearing three times a week; thriceweekly; as, a triweekly newspaper. — adv. Three times a week.
— n. A triweekly publication.
☞ This is a convenient word, but is not legitimately formed. It should mean occurring once in three weeks, as triennial means once in three years. Cf. Biweekly.