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definitions

-ics

  1. a suffix of nouns that denote a body of facts, knowledge, principles, etc., usually corresponding to adjectives ending in -ic or -ical: ethics; physics; politics; tactics.

Origin of -ics

plural of -ic, representing Latin -ica (< Greek -ika, neuter plural of -ikos), as in rhētórica (plural) rhetoric book

Usage note

Nouns ending in -ics that name fields of study, sciences, arts, professions, or the like are usually not preceded by an article and are used with a singular verb: Acoustics (the science) deals with sound. Politics (the art of government) fascinates me. In certain uses, often when preceded by a determiner like the, his, her, or their, most of these nouns can take a plural verb: The acoustics (the sound-reflecting qualities) of the hall are splendid. Their politics (political opinions) have antagonized everyone.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for -ics

-ics

suffix forming nouns (functioning as singular)
  1. indicating a science, art, or matters relating to a particular subjectaeronautics; politics
  2. indicating certain activities or practicesacrobatics

Word Origin for -ics

plural of -ic, representing Latin -ica, from Greek -ika, as in mathēmatika mathematics
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 -ics

in the names of sciences or disciplines (acoustics, aerobics, economics, etc.) it represents a 16c. revival of the classical custom of using the neuter plural of adjectives with -ikos (see -ic) to mean "matters relevant to" and also as the titles of treatises about them. Subject matters that acquired their names in English before c.1500, however, tend to remain in singular (e.g. arithmetic, logic).

Online Etymology Dictionary, © 2010 Douglas Harper
-ics in Medicine

-ics

suff.
  1. Science; art; study; knowledge; skill:pharmaceutics.
  2. Actions, activities, or practices of:macrobiotics.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.