Crossword Clue:

QUINQUENNIUM a period of five years also QUINQUENNIAD

AnswerCrossword Clue
LUSTRUMPeriod of five years.
THUAbbr. for a word also with abbrs. by its first two, or first four, or first five letters
CHILIADPeriod of a thousand years.
DECADEA certain period of years.
OCTAETERICRelating to a period of eight years.
TRICENTENARYRelating to a period of 300 years