Definitions for "bimonthly"
Occurring, done, or coming, once in two months; as, bimonthly visits; bimonthly publications.
According to Webster, bi can mean every two months or twice a month. And semi can also lead to misunderstanding. Perhaps it is better to state what you mean by simply stating either "every two months" or "twice each month."
Issue in alternate months; published six times a year
Keywords:  publication
A bimonthly publication.