• (a.) Occurring or appearing once in a fortnight; as, a fortnightly meeting of a club; a fortnightly magazine, or other publication. • (adv.) Once in a fortnight; at intervals of a fortnight. Found on http://thinkexist.com/dictionary/meaning/fortnightly/
Fort'night`ly adjective Occurring or appearing once in a fortnight; as, a fortnightly meeting of a club; a fortnightly magazine, or other publication. -- adverb Once in a fortnight; at intervals of a fortnight. Found on http://www.encyclo.co.uk/webster/F/66