every hundred years; once in a century
"the birthday of this city is being celebrated centennially"
As part of a centennial.
Centennially is an adverb indicating something that occurs every one hundred years or relating to a hundredth anniversary.
once in a hundred years
The numerical value of centennially in Chaldean Numerology is: 5
The numerical value of centennially in Pythagorean Numerology is: 8