1. pertaining to a month, or to each month.
  2. done, happening, appearing, etc., once a month: a monthly magazine.
  3. computed or determined by the month: a monthly salary.
  4. continuing or lasting for a month.
noun, plural month·lies.
  1. a periodical published once a month.
  2. Sometimes monthlies. Informal. a menstrual period.
  1. once a month; by the month.

Origin of monthly

First recorded in 1525–35; month + -ly
Related formshalf-month·ly, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for half-monthly


  1. occurring, done, appearing, payable, etc, once every month
  2. lasting or valid for a montha monthly subscription
  1. once a month
noun plural -lies
  1. a book, periodical, magazine, etc, published once a month
  2. informal a menstrual period
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for half-monthly



1530s, from month + -ly (2). As an adjective from 1570s. Old English had monaþlic, but the modern words seem to be separate formations.

Online Etymology Dictionary, © 2010 Douglas Harper