Annal ?
It is biennial.
Biennial -sg that happens every alternate year.
The adjective is quadrennial. (extension of 1-annual, 2-biennial, 3-triennial) (The archaic word for a five-year period is a lustrum.)
Pokemon events happen at random points in a year usually to coincide with a special release.
Annal ?
could it be ENTRY ??
could it be ENTRY ??
Annual means once a year. So, they are once a year events.
Biannual means twice every year.
It means year or yearly for example anniversary this is a Latin root word.
Centenary means the 100th anniversay, which would be the 100th year.
year
While not specifically "by year", chronological means "in order of occurrence in time"
Biannual.
a century
annual