FROM STRONG’S GREEK DICTIONARY (1890)

Strong’s Greek Dictionary (1890) — public domain, printed whole.

siopao σιωπάω — see-o-pah'-o — from siope (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); to be dumb (but not deaf also, like 2974 properly); figuratively, to be calm (as quiet water):--dumb, (hold) peace.

see GREEK for 4602