BIYEARLY
semiannual, biannual, biyearly, half-yearly
(adjective) occurring or payable twice each year
biennial, biyearly
(adjective) occurring every second year; “they met at biennial conventions”
semiannually, biyearly
(adverb) twice a year
biennially, biyearly
(adverb) every two years; “this festival takes places biennially”
Source: WordNet® 3.1
Etymology
Adjective
biyearly (not comparable)
Occurring every two years; biennial
Occurring twice per year; biannual
Adverb
biyearly (not comparable)
Every two years; biennially
Twice per year; biannually
Source: Wiktionary