siopao (Greek #4623)
to be dumb (but not deaf also, like 2974 properly); figuratively, to be calm (as quiet water)
KJV usage: dumb, (hold) peace.
Pronounce: see-o-pah'-o
Origin: from σιωπή (silence, i.e. a hush; properly, muteness, i.e. involuntary stillness, or inability to speak; and thus differing from 4602, which is rather a voluntary refusal or indisposition to speak, although the terms are often used synonymously)