semimonthly

nouns

a periodical that is published twice each month (or 24 issues per year)
semimonthly
is a type of (narrower)
a periodical that appears at scheduled times
serial, serial publication, series

adjectives

occurring twice a month
"a semimonthly publication"
bimonthly, semimonthly

adverbs

twice a month
"salaries are paid semimonthly"
bimonthly, semimonthly