Lexical Definition

‎ἔγγυος‎ éngyos (eng'-goo-os) guarantor ^G:A
from ‎ἐν‎ and (a limb)

surety.

• pledged (as if articulated by a member), i.e. a bondsman

Abbott-Smith

** ἔγγυος, -ου, ὁ, ἡ, [in LXX: Si 29:15, 16, II Mac 10:28 * ;]
a surety: He 7:22 (exx. from π., v. MM, Exp., xi; cf. Cremer, 222).†

Abbott-Smith References

Liddell-Scott-Jones

ἔγγυος, ον,

(ἐγγύη, compare ἀμφίγυος) secured, under good security, μνᾶς.. ἐγγύους ἐπὶτόκῳδεδανεις μένας [Refs 5th c.BC+]

__2 reliable, in comparative, ὅπλα -ώτερα [Refs 4th c.AD+]
__II substantive, ={ἐγγυητής, ἔγγυον παρέχειν} [NT+6th c.BC+]; ἔ. τῆς προξενίας giving security for.., [Refs 4th c.BC+]

_{LSJ Scripture Refs: Heb.7.22}