From enneuo; dumb (as making signs), i.e. Silent from astonishment -- speechless.
see GREEK enneuo
STRONGS NT 1769: ἐννεόςἐννεός, more correctly ἐνεός (L T Tr WH (cf. the preceding word)), ἐννεου, ὁ (it seems to be identical with ἀνεως equivalent to unused ἀναυος, ἀναος, from ἄω, αὔω to cry out, hence, without sound, mute), dumb, mute, destitute of the power of speech (Plato, Aristotle): Isaiah 56:10, cf. Proverbs 17:28; ἐνεόν μή δυνάμενον λαλῆσαι, of an idol, Baruch 6:40 (Epistle Jer.); unable to speak for terror, struck dumb, astounded: so εἱστήκεισαν ἐνεοί, stood speechless (Vulg.stabantstupefacti), Acts 9:7; Hesychius ἐμβροντηθεντες. ἐνεοί γενόμενοι. Cf. Alberti, Glossary in N. T., p. 69. In the same sense ἀπηνεώθη, Daniel 4:16 Theod., from ἀπενεόω.