Occurring every twelve months (6)
I believe the answer is:
yearly
(Other definitions for yearly that I've seen before include "Unpleasant noise" , "Approximately every 52 weeks" , "Annually" , "when Christmas comes round" , "Per annum" .)
I believe the answer is:
yearly
(Other definitions for yearly that I've seen before include "Unpleasant noise" , "Approximately every 52 weeks" , "Annually" , "when Christmas comes round" , "Per annum" .)