1. without advance preparation

    Synonyms : ad lib, ad libitum, impromptu
  2. in a spontaneous manner

    Examples :
    • this shift occurs spontaneously


  1. a post bearing a sign that gives directions or shows the way

    Synonyms : guidepost
    Type Of : sign
  2. mark with a signpost, as of a path

    Type Of : mark


  1. a neurotransmitter involved in e.g. sleep and depression and memory

    Synonyms : 5-hydroxytryptamine
    Type Of : monoamine neurotransmitter


  1. having or feeling no doubt or uncertainty; confident and assured

    Synonyms : certain
    Antonyms : unsure
    Examples :
    • was sure (or certain) she had seen it
    • was very sure in his beliefs
    • sure of her friends
  2. certain to occur; destined or inevitable

    Synonyms : certain
    Examples :
    • sudden but sure regret
    • he is sure to win
  3. impossible to doubt or dispute

    Synonyms : indisputable
    Examples :
    • indisputable (or sure) proof
  4. exercising or taking care great enough to bring assurance

    Synonyms : certain
    Examples :
    • be sure to lock the doors
  5. reliable in operation or effect

    Synonyms : certain
    Examples :
    • a sure way to distinguish the two
    • wood dust is a sure sign of termites
  6. (of persons) worthy of trust or confidence

    Synonyms : trusted
    Examples :
    • a sure (or trusted) friend
  7. definitely or positively (`sure' is sometimes used informally for `surely')

    Synonyms : certainly, for certain, for sure, sure as shooting, sure enough, surely
    Examples :
    • the results are surely encouraging
    • it's going to be a good day for sure
    • they thought he had been killed sure enough
    • he'll win sure as shooting
    • they sure smell good
    • sure he'll come
  8. certain not to fail

    Examples :
    • a sure hand on the throttle
  9. infallible or unfailing

    Examples :
    • a sure (or true) sign of one's commitment
  10. physically secure or dependable

    Examples :
    • a sure footing
    • was on sure ground


  1. a deliberately invalid argument displaying ingenuity in reasoning in the hope of deceiving someone

    Synonyms : sophism, sophistication
    Type Of : fallacy, false belief


  1. someone who engages in sports

    Synonyms : sportsman, sportswoman
    Type Of : jock, athlete
  2. play boisterously

    Synonyms : cavort, disport, frisk, frolic, gambol, lark, lark about, rollick, romp, run around, skylark
    Type Of : play
  3. (Maine colloquial) a temporary summer resident of Maine

    Synonyms : summercater
    Type Of : vacationist, vacationer
  4. wear or display in an ostentatious or proud manner

    Synonyms : boast, feature
    Type Of : have, feature
    Examples :
    • she was sporting a new hat
  5. an active diversion requiring physical exertion and competition

    Synonyms : athletics
    Type Of : diversion, recreation
  6. (biology) an organism that has characteristics resulting from chromosomal alteration

    Synonyms : mutant, mutation, variation
    Type Of : being, organism
  7. verbal wit or mockery (often at another's expense but not to be taken seriously)

    Synonyms : fun, play
    Type Of : humour, witticism, wittiness, humor, wit
    Examples :
    • he said it in sport
  8. a person known for the way she (or he) behaves when teased or defeated or subjected to trying circumstances

    Type Of : individual, soul, someone, person, mortal, somebody
    Examples :
    • a good sport
    • a poor sport
  9. the occupation of athletes who compete for pay

    Type Of : job, business, occupation, line, line of work


  1. relating to human society and its members

    Synonyms : social
    Examples :
    • societal evolution
    • societal forces


  1. fairly large in size

    Synonyms : ample, sizable
  2. large in amount or extent or degree

    Synonyms : goodish, goodly, healthy, hefty, respectable, sizable, tidy


  1. two words that can be interchanged in a context are said to be synonymous relative to that context

    Synonyms : equivalent word
    Antonyms : antonym
    Type Of : word


  1. tending to entice into a desired action or state

    Antonyms : unseductive