Well, then who are "saints" to Catholics? We say any saved person. You said that saints can be in purgatory, which leads me to think that Catholic saints are more than "the famous ones". Also, do you disagree that the passage in Romans 8 refers only to living people on earth? The context seems clear to me.
Rom. 8:26-27 : "26 In the same way, the Spirit helps us in our weakness. We do not know what we ought to pray for, but the Spirit himself intercedes for us with groans that words cannot express. 27 And he who searches our hearts knows the mind of the Spirit, because the Spirit intercedes for the saints in accordance with God's will."
In everyday life and liturgical worship, we refer to those in heaven as saints. Those who have finished the race and won the crown of everlasting glory. This is our context for the term "saint", which is why we don't usually refer to each others as "saints". We aren't there yet! However, broadly speaking, saints also refers to the saved here on earth. But again, it goes along with the term "saved" which, to Catholics, is different then your definition.
Also, do you disagree that the passage in Romans 8 refers only to living people on earth? The context seems clear to me.
Yes, technically, you are correct. It is just in normal use, we don't call each other saints. I don't have a problem with someone using the more broad term, knowing that it is how Paul used the word. The term has developed to mean something else, as words often do over time, such as the word "pray" or "worship" has different meanings today then they did 500 years ago.
Regards