Strong's Greek Concordance

G3390: μητρόπολις

mētrópolis · “capital”

Definition

a mother city, i.e. "metropolis"

KJV translates it as: chiefest city

Word origin: from G3384 (μήτηρ) and G4172 (πόλις);

μητρό-πολις, -εως, ἡ
[in LXX for אָב etc. ;]
a metropolis, chief city: ITi, subscr. (Rec.).†
(AS)

Abbott-Smith Manual Greek Lexicon (1922) via STEPBible TBESG (CC BY 4.0).