[1] : The Collaborative International Dictionary of English v.0.48

mum \mum\, n.
   silence. r. --hudibras.
   1913 webster

[2] : The Collaborative International Dictionary of English v.0.48

mum \mum\, n. g. mummere, fr. christian mumme, who first brewed
   it in 1492.
   a sort of strong beer, originally made in brunswick, germany.
   --addison.
   1913 webster

         the clamorous crowd is hushed with mugs of mum. --pope.
   1913 webster

[3] : The Collaborative International Dictionary of English v.0.48

mum \mum\, a. of imitative origin. cf. mumble.
   silent; not speaking; as, to keep mum. --thackeray.
   1913 webster

         the citizens are mum, and speak not a word. --shak.
   1913 webster

   mum's the word keep this a secret; don't tell anybody.
      pjc
see also:
mumble mum's the word 

[4] : The Collaborative International Dictionary of English v.0.48

mum \mum\, interj.
   be silent hush
   1913 webster

         mum, then, and no more.                  --shak.
   1913 webster

[5] : WordNet (r) 2.0

mum
     adj : failing to speak or communicate etc when expected to; "the
           witness remained silent" syn: silent
     n 1: of china syn: florist's chrysanthemum, florists'
          chrysanthemum, dendranthema grandifloruom, chrysanthemum
          morifolium
     2: informal terms for a mother syn: ma, mama, mamma, mom,
         momma, mommy, mammy, mummy, mater
     3: secrecy; "mum's the word"
     also: mumming, mummed
see also:
silent florist's chrysanthemum florists' chrysanthemum dendranthema grandifloruom chrysanthemum morifolium ma 
mama mamma mom momma mommy 
mammy mummy mater mumming mummed 

[6] : Moby Thesaurus II by Grady Ward, 1.0

46 moby thesaurus words for "mum":
   anaudic, aphasic, aphonic, breathless, brief, brusque, close,
   close-tongued, closemouthed, concise, curt, dumb, dumbfounded,
   dumbstricken, dumbstruck, economical of words, inarticulate,
   indisposed to talk, laconic, ma, mam, mama, mammy, mater, mom,
   mommy, mummy, mute, old woman, quiet, short, silent, snug,
   sparing of words, speechless, stricken dumb, taciturn, terse,
   tight-lipped, tongue-tied, tongueless, unloquacious, untalkative,
   voiceless, word-bound, wordless

Mum >> M Words
Mum, definition of term: Mum
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