The Collaborative International Dictionary of English v.0.48:

Moan \Moan\ (m[=o]n), v. i. [imp. & p. p. Moaned (m[=o]nd); p.
   pr. & vb. n. Moaning.] [AS. m[=ae]nan to moan, also, to
   mean; but in the latter sense perh. a different word. Cf.
   Mean to intend.]
   1. To make a low prolonged sound of grief or pain, whether
      articulate or not; to groan softly and continuously.
      [1913 Webster]

            Unpitied and unheard, where misery moans. --Thomson.
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            Let there bechance him pitiful mischances,
            To make him moan.                     --Shak.
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   2. To emit a sound like moan; -- said of things inanimate;
      as, the wind moans.
      [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

18 Moby Thesaurus words for "moaning":
   bemoaning, bewailing, grieving, howling, in mourning, keening,
   lamentation, lamenting, mourning, sigh, sighing, sobbing, sorrow,
   sorrowing, soughing, ululation, wailing, whining