The problem is NOT that I, or anybody else, hasn't defined "uncleanness". The problem is that you have declared yourself the authority of what it DOES mean. And you have NOT offered any justification whatsoever for your definition. You claim it means what you say it means and your only justification you have offered is "what else could it mean?". There is no Scriptural basis for your definition, only your own thoughts on the matter. ANY argument based on a non-existent thing is inherently riddled with human reasoning, not apologetics.
Uncleanness from a man in the O.T. is when he has an issue. ( sperm ) One can argue the point that it only means hygiene instructions as far as the marriage bed goes.
But now in the N.T., uncleanness as listed as a work of the flesh and among the sexual sins, it cannot mean anything else except masturbation when listed with fornication and lasciviousness which means sexual excessiveness.
So the problem IS avoiding defining what that uncleanness is because the believers that are engaged in it, do not want to believe that it is a sin when it has a hold on them like that, but that is one of the sins that Jesus came for to deliver us from; that infirmity in the flesh to not obey it to fulfill the lust thereof. Do not gloss over verse 19 below.
Romans 6:11 Likewise reckon ye also yourselves to be dead indeed unto sin, but alive unto God through Jesus Christ our Lord.
12 Let not sin therefore reign in your mortal body, that ye should obey it in the lusts thereof. 13 Neither yield ye your members as instruments of unrighteousness unto sin: but yield yourselves unto God, as those that are alive from the dead, and your members as instruments of righteousness unto God. 14 For sin shall not have dominion over you:........... 18 Being then made free from sin, ye became the servants of righteousness.
19 I speak after the manner of men because of the infirmity of your flesh: for as ye have yielded your members servants to uncleanness and to iniquity unto iniquity; even so now yield your members servants to righteousness unto holiness.
Now try to explain how that cannot mean masturbation at all, but then again, only God can help you see the truth here as well as our need for Him to overcome this sin & to keep us from it.
Romans 12:1I beseech you therefore, brethren, by the mercies of God, that ye present your bodies a living sacrifice, holy, acceptable unto God, which is your reasonable service.
2 And be not conformed to this world: but be ye transformed by the renewing of your mind, that ye may prove what is that good, and acceptable, and perfect, will of God.
Ephesians 6:10 Finally, my brethren, be strong in the Lord, and in the power of his might. 11 Put on the whole armour of God, that ye may be able to stand against the wiles of the devil. 12 For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places. 13 Wherefore take unto you the whole armour of God, that ye may be able to withstand in the evil day, and having done all, to stand.