ranĚdom   adj.

  1. Having no specific pattern, purpose, or objective: random movements. See Synonyms at chance.
  2. Mathematics & Statistics. Of or relating to a type of circumstance or event that is described by a probability distribution.
  3. Of or 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.

Idiom:
at random

Without a governing design, method, or purpose; unsystematically: chose a card at random from the deck.

 

 

[From at random, by chance, at great speed, from Middle English randon, speed, violence, from Old French, from randir, to run, of Germanic origin.]

 

 

chance   n.

  1.  
    1. The unknown and unpredictable element in happenings that seems to have no assignable cause.
    2. A force assumed to cause events that cannot be foreseen or controlled; luck: Chance will determine the outcome.
  2. The likelihood of something happening; possibility or probability. Often used in the plural: Chances are good that you will win. Is there any chance of rain?
  3. An accidental or unpredictable event.
  4. A favorable set of circumstances; an opportunity: a chance to escape.
  5. A risk or hazard; a gamble: took a chance that the ice would hold me.
  6. Games. A raffle or lottery ticket.
  7. Baseball. An opportunity to make a putout or an assist that counts as an error if unsuccessful.