biannual 

Occurring two times per year

Dentists strongly recommend receiving a biannual checkup to ensure a good well-being.

biannual by Define_That_Word January 2, 2018

biannual bash 

half-birthday party

"What's the occasion?"
"It's my biannual bash!"

biannual bash by hetnix February 19, 2021

Biannual Santa Claus 

Someone who comes down your chimney twice a year.

i.e. a sexual encounter that happens twice a year.

Biannual Santa Claus comes but twice a year.

Biannual Santa Claus by JohnnyBlueEyes November 23, 2011