Some say that the Greek word "πορνεία", "porneia", means sexual immorality in general, while others say that the word only describes sex outside of marriage. In the following passages, where the word is translated as "fornication", does "porneia" refer to sexual immorality in general, or to fornication only? And if it is sexual immorality in general, then what does that entail?
Matthew 5:32 KJV — But I say unto you, That whosoever shall put away his wife, saving for the cause of fornication, causeth her to commit adultery: and whosoever shall marry her that is divorced committeth adultery.
Matthew 19:9 KJV — And I say unto you, Whosoever shall put away his wife, except it be for fornication, and shall marry another, committeth adultery: and whoso marrieth her which is put away doth commit adultery.
Acts 15:29 KJV — That ye abstain from meats offered to idols, and from blood, and from things strangled, and from fornication: from which if ye keep yourselves, ye shall do well. Fare ye well.
1 Corinthians 5:1 KJV — It is reported commonly that there is fornication among you, and such fornication as is not so much as named among the Gentiles, that one should have his father's wife.
1 Corinthians 6:18 KJV — Flee fornication. Every sin that a man doeth is without the body; but he that committeth fornication sinneth against his own body.
Colossians 3:5 KJV — Mortify therefore your members which are upon the earth; fornication, uncleanness, inordinate affection, evil concupiscence, and covetousness, which is idolatry:
1 Thessalonians 4:3 KJV — For this is the will of God, even your sanctification, that ye should abstain from fornication:
1 Corinthians 5:1 suggests that incest was also called "porneia", making it mean more than mere fornication.
How was the word used in literature before the New Testament, namely in the Septuagint and in pagan Greek literature, if this information is accessible?
Thank you.