semestral

[adj] - occurring every 6 months or during each 6-month period
Found on http://www.webdictionary.co.uk/definition.php?query=semestral

semestral

semestrial adjective occurring every six months or during every period of six months
Found on http://wordnetweb.princeton.edu/perl/webwn?s=semestral

semestral

half-yearly
Found on http://phrontistery.info/s.html
No exact match found