If so, I derive my understanding from the following two verses:
1Co 7:2 Nevertheless, to avoid fornication, let every man have his own wife, and let every woman have her own husband.
1Co 10:8 Neither let us commit fornication, as some of them committed, and fell in one day three and twenty thousand.
In 7:2, Paul is teaching us that we should avoid sexual immorality by having a wife. The Greek word "porneia" translated "fornication" refers to various forms of sexual immorality like incest, adultery, sodomy, sex before marriage, etc. IOW, "fornication" in 7:2 is a sexual sin that occurs BEFORE one is married. Although it can include adultery which only occurs AFTER marriage, the context of this verse excludes adultery.
In 10:8, Paul is referring back to
Numbers 25 where the Israelite men were having sex with Moabite women. They were not married to these women. In addition to idolatry, their sin was sex before marriage. The OT calls it "whoredom/harlotry" and the NT calls it "fornication".