1. one of the surfaces forming the outside of or bounding a thing, or one of the lines bounding a geometric figure.
  2. either of the two broad surfaces of a thin, flat object, as a door, a piece of paper, etc.
  3. one of the lateral surfaces of an object, as opposed to the front, back, top, and bottom.
  4. either of the two lateral parts or areas of a thing: the right side and the left side.
  5. either lateral half of the body, especially of the trunk, of a human or animal.
  6. the dressed, lengthwise half of an animal's body, as of beef or pork, used for food.
  7. an aspect or phase, especially as contrasted with another aspect or phase: to consider all sides of a problem.
  8. region, direction, or position with reference to a central line, space, or point: the east side of a city.
  9. a slope, as of a hill.
  10. one of two or more contesting teams, groups, parties, etc.: Our side won the baseball game.
  11. the position, course, or part of a person or group opposing another: I am on your side in this issue.
  12. line of descent through either the father or the mother: grandparents on one's maternal side.
  13. the space immediately adjacent to something or someone indicated: Stand at my side.
  14. Informal. a side dish, as in a restaurant: I'll have a hamburger and a side of French fries.
  15. Usually sides. Theater.
    1. pages of a script containing only the lines and cues of a specific role to be learned by a performer.
    2. the lines of the role.
  16. Nautical. the hull portion that is normally out of the water, located between the stem and stern to port or starboard.
  17. Billiards. English(def 8).
    1. either of the two surfaces of a phonograph record or the two tracks on a audiotape.
    2. Slang.a phonograph record.
  18. Chiefly British Slang.
    1. affected manner; pretension; assumed haughtiness: to put on side.
    2. impudence; gall: He has a lot of side.
  1. being at or on one side: the side aisles of a theater.
  2. coming from one side.
  3. directed toward one side: a side blow.
  4. subordinate or incidental: a side issue.
Verb Phrases past and past participle sid·ed, present participle sid·ing.
  1. side with/against, to favor or support or refuse to support one group, opinion, etc., against opposition; take sides, as in a dispute: He always sides with the underdog.
  1. on the side, Informal.
    1. separate from the main issue or point of interest.
    2. in addition to one's regular, or known work, interest, relationships, etc.: She tried selling cosmetics on the side. He dates another girl on the side.
    3. as a side dish: a hamburger with French fries on the side.
  2. on the (adjective) side, rather more than less; tending toward (the quality or condition specified): This cake is a little on the sweet side.
  3. side by side,
    1. next to one another; together.
    2. closely associated or related; in proximity: A divided city in which democracy and communism must live side by side.
  4. take sides, to give one's support to one person or group in a dispute; be partial to one side: We were careful not to take sides for fear of getting personally involved.
  5. the far side, the farther or opposite side: the far side of the moon.

Origin of side

before 900; Middle English; Old English sīde (noun); cognate with Dutch zijde, German Seite, Old Norse sītha
Related formsside·less, adjective
Can be confusedside sighed

Synonyms for side


adjective Scot. and North England.
  1. (especially of a woman's dress or a man's beard) long and loose-flowing.

Origin of side

before 900; Middle English; Old English sīd ample, large, extending lengthwise; cognate with Old Norse sīthr long, Low German sied low


  1. a combining form meaning “iron,” used in the formation of compound words: siderolite.
Also especially before a vowel, sider-.

Origin of sidero-

< Greek sidēro-, combining form of sídēros iron Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for sider

Historical Examples of sider

British Dictionary definitions for sider


before a vowel sider-

combining form
  1. indicating ironsiderolite

Word Origin for sidero-

from Greek sidēros


  1. a line or surface that borders anything
  2. geometry
    1. any line segment forming part of the perimeter of a plane geometric figure
    2. another name for face (def. 13)
  3. either of two parts into which an object, surface, area, etc, can be divided, esp by a line, median, space, etcthe right side and the left side Related adjective: lateral
  4. either of the two surfaces of a flat objectthe right and wrong side of the cloth
  5. a surface or part of an object that extends verticallythe side of a cliff
  6. either half of a human or animal body, esp the area around the waist, as divided by the median planeI have a pain in my side
  7. the area immediately next to a person or thinghe stood at her side
  8. a district, point, or direction within an area identified by reference to a central pointthe south side of the city
  9. the area at the edge of a room, road, etc, as distinguished from the middle
  10. aspect or partlook on the bright side; his cruel side
  11. one of two or more contesting factions, teams, etc
  12. a page in an essay, book, etc
  13. a position, opinion, etc, held in opposition to another in a dispute
  14. line of descenthe gets his brains from his mother's side
  15. informal a television channel
  16. billiards snooker spin imparted to a ball by striking it off-centre with the cueUS and Canadian equivalent: English
  17. British slang insolence, arrogance, or pretentiousnessto put on side
  18. on one side set apart from the rest, as provision for emergencies, etc, or to avoid muddling
  19. on the heavy side tending to be too heavy
  20. on the side
    1. apart from or in addition to the main object
    2. as a sideline
    3. USas a side dish
    4. bit on the side See bit 1 (def. 11)
  21. side by side
    1. close together
    2. (foll by with)beside or near to
  22. take sides to support one group, opinion, etc, as against another
  1. being on one side; lateral
  2. from or viewed as if from one side
  3. directed towards one side
  4. not main; subordinate or incidentalside door; side road
  1. (intr usually foll by with) to support or associate oneself with a faction, interest, etc
  2. (tr) to provide with siding or sides
  3. (tr; often foll by away or up) Northern English dialect to tidy up or clear (dishes, a table, etc)

Word Origin for side

Old English sīde; related to sīd wide, Old Norse sītha side, Old High German sīta
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 sider



Old English side "flanks of a person, the long part or aspect of anything," from Proto-Germanic *sithon (cf. Old Saxon sida, Old Norse siða, Danish side, Swedish sida, Middle Dutch side, Dutch zidje, Old High German sita, German Seite), from adjective *sithas "long" (cf. Old English sid "long, broad, spacious," Old Norse siðr "long, hanging down"), from PIE root *se- "long, late" (see soiree).

Original sense preserved in countryside. Figurative sense of "position or attitude of a person or set of persons in relation to another" (cf. choosing sides) first recorded mid-13c. Meaning "one of the parties in a transaction" is from late 14c.; sense in a sporting contest or game is from 1690s. Meaning "music on one side of a phonograph record" is first attested 1936. Phrase side by side "close together and abreast" is recorded from c.1200. Side-splitting "affecting with compulsive laughter" is attested by 1825.



late 15c., "to cut into sides" (of meat), from side (n.). Meaning "to support one of the parties in a discussion, dispute, etc.," is first attested 1590s, from side (n.) in the figurative sense; earlier to hold sides (late 15c.). Related: Sided; siding.



late 14c., from side (n.).

Online Etymology Dictionary, © 2010 Douglas Harper

sider in Medicine


  1. Iron:sideropenia.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Idioms and Phrases with sider


In addition to the idioms beginning with side

  • side against
  • side by side
  • side of the tracks
  • side street
  • side with

also see:

  • blind spot (side)
  • bright side
  • can't hit the broad side of a barn
  • choose up (sides)
  • get on someone's good side
  • get up on the wrong side of bed
  • in good with (on someone's good side)
  • know which side of bread is buttered
  • laugh out of the other side of one's mouth
  • let someone (the side) down
  • on someone's side
  • on the safe side
  • on the side
  • on the side of the angels
  • other side of the coin
  • right side of the tracks
  • right-side out
  • right-side up
  • seamy side
  • split one's sides
  • sunny-side up
  • take aside (to one side)
  • take sides
  • this side of
  • thorn in one's flesh (side)
  • work both sides of the street
  • wrong side of
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.