adjective. Happening every two years.

adjective. Happening twice a year; semiyearly.

adverb. Every two years.

adverb. Twice a year; semiyearly.

adjective. Occurring every two years; biennial

adjective. Occurring twice per year; biannual

adverb. Every two years; biennially

adverb. Twice per year; biannually

adverb. every two years

adjective. occurring or payable twice each year

adverb. twice a year

adjective. occurring every second year

"There's still the biyearly Northwestern minefield and the quadrennial recruiting junket to Hawaii to deal with, and that's beyond the fact the Beat Michigan Club isn't exactly exclusive these last two years."

periodic  periodical