halfhourly

[ haf-ouuhr-lee, -ou-er-, hahf- ]

adjective

1. half-hour ( def 3 ).
2. occurring every half-hour:

   a halfhourly interruption.

adverb

1. at half-hour intervals:

   The bell rang halfhourly.

Word History and Origins

Origin of halfhourly¹

First recorded in 1800–10; half + hourly