1. silently , σῖγα ἔχειν to be silent , (Sophocles Tragicus); κάθησο σῖγα (Aristophanes Comicus); alone, σῖγα hush! be still! (Aeschulus Tragicus):—;the public crier proclaiming silence said σῖγα πᾶς (i.e. ἔστω); (Aristophanes Comicus)

2. under one's breath, in a whisper, secretly , (Aeschulus Tragicus) (ML)