Those who were strangers generally, and who owned no landed property.
Strangers dwelling in another country without being naturalized (Leviticus 22:10; Psalms 39:12).
Both of these classes were to enjoy, under certain conditions, the same rights as other citizens (Leviticus 19:33,34; Deuteronomy 10:19). They might be naturalized and permitted to enter into the congregation of the Lord by submitting to circumcision and abandoning idolatry (Deuteronomy 23:3-8).
This term is used (Ephesians 2:12) to denote persons who have no interest in Christ.
These dictionary topics are from M.G. Easton M.A., D.D., Illustrated Bible Dictionary, Third Edition, published by Thomas Nelson, 1897. Public Domain, copy freely.
Easton, Matthew George. "Entry for 'Alien'". "Easton's Bible Dictionary".