adjective

temporarily unable or unwilling to speak.

they stood dumb while the attacker poured out a stream of abuse

speechless,tongue-tied,wordless,silent,at a loss for words,voiceless,inarticulate,taciturn,uncommunicative,untalkative,tight-lipped,close-mouthed,saying nothing,mum

verb

make dumb or unheard; silence.

a splendour that dazed the mind and dumbed the tongue