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halfhourly

American  
[haf-ouuhr-lee, -ou-er-, hahf-] / ˈhæfˈaʊər li, -ˈaʊ ər-, ˈhɑf- /

adjective

  1. half-hour.

  2. occurring every half-hour.

    a halfhourly interruption.


adverb

  1. at half-hour intervals.

    The bell rang halfhourly.

Etymology

Origin of halfhourly

First recorded in 1800–10; half + hourly