dumbly

Concise Oxford English Dictionary © 2008 Oxford University Press:
dumb/dʌm/

▶adjective

• 1 unable to speak, typically because of congenital deafness.

  ■ (of animals) unable to speak as a natural state.

  ■ temporarily unable or unwilling to speak.

• 2 informal, chiefly N. Amer. stupid.

• 3 (of a computer terminal) having no independent processing capability.

▶verb

• 1 (dumb something down or dumb down) informal make or become less intellectually challenging.

• 2 literary make silent.

– derivatives
dumbly adverb,
dumbness noun.

– origin OE, of Gmc origin.

usage: In the sense meaning ‘not able to speak’, dumb has been overwhelmed by the sense ‘stupid’ to such an extent that the use of the first sense is now almost certain to cause offence. Alternatives such as speech-impaired should be used instead.