We have multiple parties in Canada.

There may be a minority government elected, with 40% of the seats, and 30%, 20%, 10% to other parties.

The 40% party will be described as winning the most seats.

Ha, I gotta say after reading your reply I feel kind of dumb for even saying the 80%; I had blinders on. Most, when it's relative, is the highest of a set even if that number is super low. Totally spaced on that when I asked, but I was fixated on how it's used to define something that's a percentage like in the 65% example. It happens so frequently in journalism and it's frustrating because it's trying to make an argument that sometimes the numbers themselves don't support.

Anyway, appreciate you reminding me (and I deserved to feel dumb so also making me feel a bit dumb about it).

Yes, that is definition 1 (merriam-webster). This definition is often invoked by saying "the" before "most," as you did.

It's a different definition than defn 2 (m-w), which is what is used when saying "Most farms are not owned by farmers."

"The 40% party won the most seats" carries a different meaning than "The 40% party won most seats"

It's more complicated. They got "the most" seats but they didn't get "most" seats.

Pure "most" is implicitly that option versus all the rest.