n.; pl. Decennaries [ L. decennium a period of ten years; decem ten + annus a year. ] 1. A period of ten years. [ 1913 Webster ]

2. (O. Eng. Law) A tithing consisting of ten neighboring families. Burrill. [ 1913 Webster ]

a. [ L. undecim eleven (unus one + decem ten) + -ennary as in decennary. Cf. Undecennial. ] Occurring once in every period of eleven years; undecennial. [ 1913 Webster ]

An undecennary account laid before Parliament. E. Stiles. [ 1913 Webster ]