(Philately) of or relating to mail that is carried at the lowest rate
(Philately) by fourth-class mail
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014

fourth′ class′

(in the U.S. Postal Service) the class of mail consisting of merchandise weighing one pound or more and not sealed against inspection.
[1860–65, Amer.]


1. of, pertaining to, or designated as a class next below third.
2. by fourth-class mail.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
References in periodicals archive ?
As 'keepers of peace, sources of hope, and defenders of the state and its people,' the new fourth-class cadets must 'endure the pain and pass through all critical processes [because they] will need all the lessons from these experiences to make the decisions and attain meaningful accomplishments,' said Madrigal, a member of PMA 'Sandiwa' Class of 1985.
A total of 350 second-class police officers will be promoted to first class; 500 third-class police officers will be promoted to second class; 350 fourth-class police officers will be upgraded to third class; and hundreds of other officers will be promoted to fourth class.
SIR - The Government of Wales Act, passed on July 25, far from settling the democratic process in Wales 'for generations at least if not for ever' (as Peter Hain hopes) should be repealed as soon as possible as it makes us fourth-class citizens in our own land.
At the academy, this training begins with basic cadet training, once conducted under the umbrella of a training structure known as the "fourth-class" system, with upperclass cadets in charge of training the new fourth-class--freshmen--cadets.
Only half of the children at Rushbrook National School showed up for classes yesterday after the fourth-class pupil was admitted to Cork University Hospital.
A fourth-class municipality (population: 11,290 as of 2015), Salcedo is one of Ilocos Sur's mango-producing areas.
Of the finalists, only three are full-fledged cities - Vigan, a fourth-class city; Tacurong, a fourth-class component city; and Kidapawan, a second-class city.
A 19-year-old fourth-class cadet of the Philippine Military Academy died on Labor Day (Monday, May 1) from internal bleeding due to stomach ulcers that were detected after he was accepted into the academy, one of his physicians said on Wednesday (May 3).