Usage: 6 forms in 15 verses
Form Translated As     In Verse(s)
εγγαστριμύθων of the ones who deliver oracles LXX.Isa.44.25
εγγαστριμύθω delivering an oracle LXX.1Sam.28.8
who delivers oracles LXX.1Chr.10.13
εγγαστριμύθουσ delivering oracles LXX.Isa.19.3
delivering up oracles LXX.1Sam.28.9
ones who deliver oracles LXX.1Sam.28.3LXX.2Kgs.21.6LXX.2Chr.33.6
who deliver oracles LXX.Isa.8.19
εγγαστριμύθοισ ones who deliver oracles LXX.Lev.19.31LXX.Lev.20.6
εγγαστρίμυθοσ a deliverer of oracles LXX.Lev.20.27
one who delivers oracles LXX.Deut.18.11
who delivers oracles LXX.1Sam.28.7
εγγαστρίμυθον who delivers oracles LXX.1Sam.28.7

Liddell-Scott-Jones

ἐγγαστρίμυθος (engastrimuthos) one who delivers oracles G:A

ἐγγαστρίμυθος-μῡθος, ον,

ventriloquist, mostly of women who delivered oracles by this means: hence, ={ἐγγαστρίμυθοςμαντις}, [LXX+5th c.BC+]; also, the familiar spirit of such a person, [LXX]

LSJ Scripture Refs: LXX.Lev.19.31 ☩ LXX.1Kgs.28.8