Usage: 7 forms in 26 verses
Form Translated As     In Verse(s)
γαμβρών his sons-in-law LXX.Gen.19.14
γαμβρώ father-in-law LXX.Num.10.29
his father-in-law LXX.Exod.18.7LXX.Exod.18.8LXX.Exod.18.15
γαμβρόσ an in-law LXX.1Sam.18.18
father-in-law LXX.Exod.18.1LXX.Exod.18.2LXX.Exod.18.5LXX.Exod.18.12LXX.Exod.18.17
his father-in-law LXX.Judg.19.4LXX.Judg.19.7LXX.Judg.19.9
in-law LXX.Neh.13.28
son-in-law LXX.Judg.15.6LXX.1Sam.22.14LXX.2Kgs.8.27LXX.Neh.6.18
your father-in-law LXX.Exod.18.6
γαμβρόν father-in-law LXX.Exod.18.27
γαμβρούσ his sons-in-law LXX.Gen.19.14
γαμβρού father-in-law LXX.Exod.18.12LXX.Judg.4.11
of his father-in-law LXX.Exod.18.24
γαμβροί in-laws LXX.Gen.19.12

Liddell-Scott-Jones

γαμβρός (gambros) an in-law G:N-M

γαμβρός, ,

connexion by marriage, [Refs 5th c.BC+]

__I son-in-law, [Refs 8th c.BC+]
__II brother-in-law, i.e. sister's husband, [Refs 8th c.BC+]; or, wife's brother, [Refs 5th c.BC+]
__III ={πενθερός}, father-in-law, [LXX+5th c.BC+]
__IV Doric dialect and Aeolic dialect, bridegroom, wooer, [Refs 7th c.BC+]. (Cf. Sanskrit jārá- (from ĝ[mmacrnull]ró- 'lover'.)

LSJ Scripture Refs: LXX.Exod.3.1