definition of
mum

[1] #1 mum s. [silent] failing to speak or communicate etc when expected to; "the witness remained silent". wn

[2] #2 mum n. [florist's chrysanthemum, florists' chrysanthemum, Dendranthema grandifloruom, Chrysanthemum morifolium] of China. wn

[3] #3 mum n. [ma, mama, mamma, mom, momma, mommy, mammy, mummy] informal terms for a mother. wn

[4] #4 mum n. secrecy; "mum's the word". wn