The Collaborative International Dictionary
Obmutescence
Obmutescence \Ob`mu*tes"cence\ ([o^]b`m[-u]*t[e^]s"sens), n. [L. obmutescens, p. pr of obmutescere to become dumb; ob (see Ob-) + mutescere to grow dumb, fr. mutus dumb.]
A becoming dumb; loss of speech.
--Sir T. Browne.A keeping silent or mute.
--Paley.
Wiktionary
obmutescence
n. silence; inability or refusal to speak.