Dictionary.com
definitions

random

[ran-duhm]
See more synonyms for random on Thesaurus.com
adjective
  1. proceeding, made, or occurring without definite aim, reason, or pattern: the random selection of numbers.
  2. Statistics. of or characterizing a process of selection in which each item of a set has an equal probability of being chosen.
  3. Building Trades.
    1. (of building materials) lacking uniformity of dimensions: random shingles.
    2. (of ashlar) laid without continuous courses.
    3. constructed or applied without regularity: random bond.
  4. Slang.
    1. unknown, unidentified, or suspiciously out of place: A couple of random guys showed up at the party.
    2. odd or unpredictable, often in an amusing way: my totally random life.
noun
  1. something that is random, or a random state or condition: different statistical methods used to estimate randoms.
  2. Slang.
    1. a person or thing that is unknown, unidentified, or suspiciously out of place.
    2. a person or thing that is odd or unpredictable.
  3. Chiefly British. bank3(def 7b).
adverb
  1. Building Trades. without uniformity: random-sized slates.
Idioms
  1. at random, without definite aim, purpose, method, or adherence to a prior arrangement; in a haphazard way: Contestants were chosen at random from the studio audience.

Origin of random

1275–1325; Middle English raundon, random < Old French randon, derivative of randir to gallop < Germanic
Related formsran·dom·ly, adverbran·dom·ness, nounnon·ran·dom, adjectivenon·ran·dom·ly, adverbnon·ran·dom·ness, noun

Synonyms for random

See more synonyms for on Thesaurus.com
1. haphazard, chance, fortuitous.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Related Words for at random

seldom, sometimes, infrequently, sporadically, hardly, periodically, frantically, madly, wildly, instinctively, indiscriminately, aimlessly, anyway, haphazard, headlong, jumbled, incidental, contingent, haphazardly, hit-or-miss
British Dictionary definitions for at random

random

adjective
  1. lacking any definite plan or prearranged order; haphazarda random selection
  2. statistics
    1. having a value which cannot be determined but only described probabilisticallya random variable
    2. chosen without regard to any characteristics of the individual members of the population so that each has an equal chance of being selectedrandom sampling
  3. informal (of a person) unknownsome random guy waiting for a bus
noun
  1. at random in a purposeless fashion; not following any prearranged order
Derived Formsrandomly, adverbrandomness, noun

Word Origin for random

C14: from Old French randon, from randir to gallop, of Germanic origin; compare Old High German rinnan to run
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 at random

random

adj.

"having no definite aim or purpose," 1650s, from at random (1560s), "at great speed" (thus, "carelessly, haphazardly"), alteration of Middle English noun randon "impetuosity, speed" (c.1300), from Old French randon "rush, disorder, force, impetuosity," from randir "to run fast," from Frankish *rant "a running" or some other Germanic source, from Proto-Germanic *randa (cf. Old High German rennen "to run," Old English rinnan "to flow, to run;" see run (v.)).

In 1980s U.S. college student slang it began to acquire a sense of "inferior, undesirable." (A 1980 William Safire column describes it as a college slang noun meaning "person who does not belong on our dormitory floor.") Random access in reference to computer memory is recorded from 1953. Related: Randomly; randomness.

Online Etymology Dictionary, © 2010 Douglas Harper
at random in Science

random

[răn′dəm]
  1. Relating to a type of circumstance or event that is described by a probability distribution.
  2. Relating to an event in which all outcomes are equally likely, as in the testing of a blood sample for the presence of a substance.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Idioms and Phrases with at random

at random

Without order or fixed purpose, haphazardly, as in Jackson Pollock dropped paints on canvas seemingly at random. Originally this phrase meant “very speedily” and “heedlessly.” Shakespeare had the present usage in 1 Henry VI (5:3): “He talks at random; sure the man is mad.” [Late 1500s]

random

see at random.

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.