Definition (full): to draw over, to become as uncircumcised
Strong's Exhaustive Concordance
From epi and spao; to draw over, i.e. (with akrobustia implied) efface the mark of circumcision (by recovering with the foreskin) -- become uncircumcised.
KJV: Is any man called being circumcised? let him not become uncircumcised. Is any called in uncircumcision? let him not be circumcised.
NASB: Was any man called when he was already circumcised? He is not to become uncircumcised. Has anyone been called in uncircumcision? He is not to be circumcised.