Obmutescence
Obmutescence (ob`mu*tes"sens) , noun
[Latin obmutescens, p. pr of obmutescere to become dumb; ob (see Ob-) + mutescere to grow dumb, from mutus dumb.]
1.
A becoming dumb; loss of speech. — Sir T. Browne
2.
A keeping silent or mute. — Paley