Akrobystia (G203) literally refers to the foreskin but is used in the NT as a technical term for the state of being uncircumcised — and by extension, for Gentiles as a group. Paul uses it extensively in Romans and Galatians to argue that justification came to Abraham while in akrobystia (before his circumcision), making him father of believing Gentiles too.
Paul's argument in Romans 4:9–12 is pivotal: Abraham was justified by faith while in akrobystia — uncircumcised. This means the blessing of justification belongs to all who share Abraham's faith, regardless of physical circumcision. The foreskin/circumcision distinction is transcended in Christ (Galatians 5:6; 6:15) — what matters is new creation. Jew and Gentile together form one body.