Tough - adjective 1. strong and durable; not easily broken or cut. 2. not brittle or tender. 3. difficult to masticate, as food. 4. of viscous consistency, as liquid or semiliquid matter: tough molasses. 5. capable of great endurance; sturdy; hardy. I suppose I'm thinking more of number 5 when I think of humans being tough. They haven't backed down from any of the specied listed above despite being woefully mismatched at times and have even managed to come out on top at times despite the opposition. This is far more impressive than say some single minded drugged up Jem H'dar.
Humans have the sturdiness/hardyness of cockroaches. An individual human or an individual human ship is easily bitch-slapped. It's just that the humans keep coming over the corpses of their dead, and they keep adapting to the pesticides used against them. This is NOT toughness. Toughness requires for the individual human or ship to be hard to bitch-slap, to be able to take a lot of damage before succumbing.
I'm not even sure you read the definition of the word when you posted it to me. 5. capable of great endurance; sturdy; hardy. Humans do not have the sturdiness/hardyness of cockroaches. They have the studiness/hardyness of humans because you know...their humans. You also say that "Toughness requires for the individual human or ship to be hard to bitch-slap (a term you seem to really enjoy), to be able to take a lot of damage before succumbing." Sounds like humans to me.
Use of Time Really? First, don't think I haven't noticed how you did not take the definition for toughness from my link, but from somewhere else in order to take a few words out of context, to try and give them a meaning they do not have. Second, trekverse 'humans have the sturdiness/hardyness of cockroaches' is a comparison. A quite adequate one, too. That you have trouble stomaching it is irrelevant. Third, humans are easily killed by almost everyone of note and his idiot cousin in the trekverse. Not even close to being able to take a lot of damage before succumbing.
Your definition tough (tf) adj. tough·er, tough·est 1. Able to withstand great strain without tearing or breaking; strong and resilient: a tough all-weather fabric. 2. Hard to cut or chew: tough meat. 3. Physically hardy; rugged: tough mountaineers; a tough cop. 4. Severe; harsh: a tough winter. 5. a. Aggressive; pugnacious. b. Inclined to violent or disruptive behavior; rowdy or rough: a tough street group. 6. Demanding or troubling; difficult: skipping the toughest questions. 7. Strong-minded; resolute: a tough negotiator. 8. Slang Unfortunate; too bad: a tough break. 9. Slang Fine; great. n. A violent or rowdy person; a hoodlum or thug. Idiom: tough it out Slang To get through despite hardship; endure: "It helps if one was raised to tough it out" (Gail Sheehy). Check out the idiom especially. This is more along the lines of what I was thinking when I think of a tough species. The only reason we are arguing is because you are going off of the 1st definition and I am using the idiom. That's it. Oh, and to your second point, I can handle the cockroach analogy just fine...becuase I'm human...AND TOUGH!
The idiom is 'tough it out', NOT 'tough'. Different word structure; different meaning. You're grasping at straws.
We are discussing who is the toughest Star Trek species. Which to be honest typing that out made me feel incredibly nerdy right now. Grasping at straws? Idioms perhaps but not straws. The word has several different meanings which can support both views here. If you look at my prior posts I have used several words and analogies identified in the definition you provided. I have called them resiliant, brave in the face of a superior opponoent which I would consider "strong-minded" and they have on several occasions "toughed it out." (If you permit me to use the idiom) Now reading your definition if appears I didn't put enough emphasis on durability in which the humans would definitely be lacking when compared to the races mentioned in the OP. I guess it all depends on which components of the definition you choose to put greater weight on. I see your point.
It looks like opinion is leaning towards humans which I didn't expect. We're good, don't get me wrong, but I considered humans to be pushovers (other than the exceptional main characters).