The Collaborative International Dictionary of English v.0.48:

Random \Ran"dom\, a.
   1. Going at random or by chance; done or made at hazard, or
      without settled direction, aim, or purpose; hazarded
      without previous calculation; left to chance; haphazard;
      as, a random guess.
      [1913 Webster]

            Some random truths he can impart.     --Wordsworth.
      [1913 Webster]

            So sharp a spur to the lazy, and so strong a bridle
            to the random.                        --H. Spencer.
      [1913 Webster]

   2. (Statistics) Of, pertaining to, or resulting from a
      process of selection from a starting set of items, in
      which the probability of selecting any one object in the
      starting set is equal to the probability of selecting any
      other.
      [PJC]

   3. (Construction) of unequal size or shape; made from
      components of unequal size or shape.
      [PJC]

   at random in a manner so that all possible results have an
      equal probability of occurrence; for processes, each
      possible result is counted separately although the same
      type of result may occur more than once .

   Random courses (Masonry), courses of stone of unequal
      thickness.

   Random shot, a shot not directed or aimed toward any
      particular object, or a shot with the muzzle of the gun
      much elevated.

   Random work (Masonry), stonework consisting of stones of
      unequal sizes fitted together, but not in courses nor
      always with flat beds.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Random \Ran"dom\ (r[a^]n"d[u^]m), n. [OE. randon, OF. randon
   force, violence, rapidity, [`a] randon, de randon, violently,
   suddenly, rapidly, prob. of German origin; cf. G. rand edge,
   border, OHG. rant shield, edge of a shield, akin to E. rand,
   n. See Rand, n.]
   1. Force; violence. [Obs.]
      [1913 Webster]

            For courageously the two kings newly fought with
            great random and force.               --E. Hall.
      [1913 Webster]

   2. A roving motion; course without definite direction; want
      of direction, rule, or method; hazard; chance; -- commonly
      used in the phrase at random, that is, without a settled
      point of direction; at hazard.
      [1913 Webster]

            Counsels, when they fly
            At random, sometimes hit most happily. --Herrick.
      [1913 Webster]

            O, many a shaft, at random sent,
            Finds mark the archer little meant!   --Sir W.
                                                  Scott.
      [1913 Webster]

   3. Distance to which a missile is cast; range; reach; as, the
      random of a rifle ball. --Sir K. Digby.
      [1913 Webster]

   4. (Mining) The direction of a rake-vein. --Raymond.
      [1913 Webster]

WordNet (r) 3.0 (2006):

random
    adj 1: lacking any definite plan or order or purpose; governed
           by or depending on chance; "a random choice"; "bombs fell
           at random"; "random movements" [ant: nonrandom]

Moby Thesaurus II by Grady Ward, 1.0:

138 Moby Thesaurus words for "random":
   accidental, adventitious, adventitiously, aimless, aleatoric,
   aleatory, amorphous, any which way, anyhow, anywise, arbitrarily,
   arbitrary, around, at random, blobby, blurred, blurry, broad,
   by chance, capricious, casual, casually, causeless, chance,
   chance-medley, chancy, chaotic, confused, designless, desultory,
   disarticulated, discontinuous, disjunct, disordered, dispersed,
   disproportionate, driftless, dysteleological, erratic, erratically,
   fitful, foggy, formless, fortuitous, fortuitously, frivolous,
   fuzzy, general, gratuitous, haphazard, haphazardly, hazy,
   helter-skelter, hit-or-miss, ill-defined, immethodical, imprecise,
   inaccurate, inchoate, incidental, incidentally, incoherent,
   indecisive, indefinable, indefinite, indefinitely, indeterminable,
   indeterminate, indiscriminate, indiscriminately, indistinct,
   inexact, inexplicable, irregular, irregularly, lax, loose,
   meaningless, mindless, misshapen, nonspecific, nonsymmetrical,
   nonsystematic, nonuniform, obscure, occasional, occasionally, odd,
   orderless, planless, potluck, promiscuous, purposeless,
   random shot, randomly, senseless, serendipitous, serendipitously,
   shadowed forth, shadowy, shapeless, spasmodic, sporadic,
   stochastic, straggling, straggly, stray, sweeping, systemless,
   unaccountable, unarranged, uncalculated, unclassified, unclear,
   undefined, undestined, undetermined, undirected, ungraded,
   unjoined, unmethodical, unmotivated, unordered, unorganized,
   unplain, unplanned, unpremeditated, unpremeditatedly, unsorted,
   unspecific, unspecified, unsymmetrical, unsystematic,
   unsystematically, ununiform, vague, veiled, wandering



The Jargon File (version 4.4.7, 29 Dec 2003):

random
 adj.

    1. Unpredictable (closest to mathematical definition); weird. ?The system's
    been behaving pretty randomly.?

    2. Assorted; undistinguished. ?Who was at the conference?? ?Just a bunch of
    random business types.?

    3. (pejorative) Frivolous; unproductive; undirected. ?He's just a random
    loser.?

    4. Incoherent or inelegant; poorly chosen; not well organized. ?The program
    has a random set of misfeatures.? ?That's a random name for that function.?
    ?Well, all the names were chosen pretty randomly.?

    5. In no particular order, though deterministic. ?The I/O channels are in a
    pool, and when a file is opened one is chosen randomly.?

    6. Arbitrary. ?It generates a random name for the scratch file.?

    7. Gratuitously wrong, i.e., poorly done and for no good apparent reason.
    For example, a program that handles file name defaulting in a particularly
    useless way, or an assembler routine that could easily have been coded
    using only three registers, but redundantly uses seven for values with
    non-overlapping lifetimes, so that no one else can invoke it without first
    saving four extra registers. What randomness!

    8. n. A random hacker; used particularly of high-school students who soak
    up computer time and generally get in the way.

    9. n. Anyone who is not a hacker (or, sometimes, anyone not known to the
    hacker speaking); the noun form of sense 2. ?I went to the talk, but the
    audience was full of randoms asking bogus questions?.

    10. n. (occasional MIT usage) One who lives at Random Hall. See also J.
    Random, some random X.

    11. [UK] Conversationally, a non sequitur or something similarly
    out-of-the-blue. As in: ?Stop being so random!? This sense equates to
    ?hatstand?, taken from the Viz comic character ?Roger Irrelevant - He's
    completely Hatstand.?


The Free On-line Dictionary of Computing (30 December 2018):

random

   1. Unpredictable (closest to mathematical definition); weird.
   "The system's been behaving pretty randomly."

   2. Assorted; undistinguished.  "Who was at the conference?"
   "Just a bunch of random business types."

   3. (pejorative) Frivolous; unproductive; undirected.  "He's
   just a random loser."

   4. Incoherent or inelegant; poorly chosen; not well organised.
   "The program has a random set of misfeatures."  "That's a
   random name for that function."  "Well, all the names were
   chosen pretty randomly."

   5. In no particular order, though deterministic.  "The I/O
   channels are in a pool, and when a file is opened one is
   chosen randomly."

   6. Arbitrary.  "It generates a random name for the scratch
   file."

   7. Gratuitously wrong, i.e. poorly done and for no good
   apparent reason.  For example, a program that handles file
   name defaulting in a particularly useless way, or an assembler
   routine that could easily have been coded using only three
   registers, but redundantly uses seven for values with
   non-overlapping lifetimes, so that no one else can invoke it
   without first saving four extra registers.  What randomness!

   8.  A random hacker; used particularly of high-school students
   who soak up computer time and generally get in the way.

   9.  Anyone who is not a hacker (or, sometimes, anyone not
   known to the hacker speaking).  "I went to the talk, but the
   audience was full of randoms asking bogus questions".

   10.  (occasional MIT usage) One who lives at Random Hall.  See
   also J. Random, some random X.

   [Jargon File]

   (1995-12-05)