1. Destitute or deprived of the faculty of speech.
2. Not speaking for a time; dumb; mute; silent.
Speechless with wonder, and half dead with fear. --Addison.
-- Speech*less*ly, adv. -- Speech*less*ness, n.
adv : without speaking; "he stood up soundlessly and speechlessly
and glided across the hallway and through a door"