ca·su·al /ˈkæʒwəl, ˈkæʒəwəl, ˈkæʒəl/
  (a.)偶然的,碰巧的;臨時的,不定期的;漫不經心的,隨便的,非正式的
  casual
  非正式 不定期
  Cas·u·al a.
  1. Happening or coming to pass without design, and without being foreseen or expected; accidental; fortuitous; coming by chance.
     Casual breaks, in the general system.   --W. Irving.
  2. Coming without regularity; occasional; incidental; as, casual expenses.
     A constant habit, rather than a casual gesture.   --Hawthorne.
  Syn: -- Accidental; fortutious; incidental; occasional; contingent; unforeseen. See Accidental.
  Cas·u·al, n. One who receives relief for a night in a parish to which he does not belong; a vagrant.
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  casual
       adj 1: marked by blithe unconcern; "an ability to interest casual
              students"; "showed a casual disregard for cold
              weather"; "an utterly insouciant financial policy";
              "an elegantly insouciant manner"; "drove his car with
              nonchalant abandon"; "was polite in a teasing
              nonchalant manner" [syn: insouciant, nonchalant]
       2: without or seeming to be without plan or method; offhand; "a
          casual remark"; "information collected by casual methods
          and in their spare time"
       3: suited for everyday use; "casual clothes"; "everyday
          clothes" [syn: everyday]
       4: occurring or appearing or singled out by chance; "their
          accidental meeting led to a renewal of their friendship";
          "seek help from casual passers-by"; "a casual meeting"; "a
          chance occurrence" [syn: accidental, chance(a)]
       5: hasty and without attention to detail; not thorough; "a
          casual (or cursory) inspection failed to reveal the
          house's structural flaws"; "a passing glance";
          "perfunctory courtesy" [syn: cursory, passing(a), perfunctory]
       6: employed in a specified capacity from time to time; "casual
          employment"; "a casual correspondence with a former
          teacher"; "an occasional worker" [syn: occasional]
       7: characterized by a feeling of irresponsibility; "a broken
          back is nothing to be casual about; it is no fooling
          matter" [syn: fooling]
       8: natural and unstudied; "using their Christian names in a
          casual way"; "lectured in a free-and-easy style" [syn: free-and-easy]
       9: not showing effort or strain; "a difficult feat performed
          with casual mastery"; "careless grace" [syn: effortless]