UNDECENNIAL
Source: 567
Un′de‐cen″ni‐al (?), a. [[See Undecennary, and cf. Decennial.]] Occurring or observed every eleventh year; belonging to, or continuing, a period of eleven years; undecennary; as, an undecennial festival.
Source: 567
Un′de‐cen″ni‐al (?), a. [[See Undecennary, and cf. Decennial.]] Occurring or observed every eleventh year; belonging to, or continuing, a period of eleven years; undecennary; as, an undecennial festival.