Endurance
Surviving multiple hit from someone clearly stronger than you is endurance. Zodd's attacks are the maximum Guts can take.
Example

eople can possibly survive car crashes despite car being able to ram through walls.
"The ability to withstand hardship or adversity; the ability to sustain a prolonged stressful effort or activity."
This doesn't at all describe endurance as "continuously taking hits". It describes how long one can go without exhaustion.
And about your car analogy: Yes, as long as no vital body parts are damaged beyond repair, they're going to be fine. That doesn't mean bullets don't kill people, or that they can just keep taking car crashes.
This is basically my point. Guts took hits from Zodd and was able to continue the battle.
My point is that you were describing it as if the power of the attack actually accounted for something, which it doesn't. "He survived hits from someone who is 8-B, 9-A attacks aren't killing him anytime soon".
This brings me back to your car analogy: Just because you can survive an 8-B attack that surpassed the durability of your body doesn't mean that a well-placed 9-A+ attack won't kill you.
The bird throws three chickens legs at you. I'm pretty sure Guts, a war veteran, can dodge that. Also has the superior range with arrows and his arm cannon.
I wasn't arguing that Guts would lose -- I cannot even do that as the OP. I was explaining why I did this matchup in the first place. Overall I think they're very even, as they both have advantages in different areas; Guts is much more determined and skilled, while Colonel has a raw power and durability advantage as well as some versatility.