Douglas Harper's Etymology Dictionary
Wiktionary
semi-annual
a. (alternative spelling of semiannual English)
Usage examples of "semi-annual".
Like poor Celia Greenway would never again know the joy of a semi-annual clearance sale at Bloomies, the scent of new leather pumps, or the thrill of finding that one-of-a-kind bag in the half-off bin.
One night Cal ran into Rabbit Holman, who was up from San Ardo on his semi-annual drunk.