The spell Remove curse only states:

At your touch, all curses affecting one creature or object end. If the object is a cursed magic item, its curse remains, but the spell breaks its owner’s attunement to the object so it can be removed or discarded.

What can be considered as "cursed"? If a spell has been casted on a weapon and the spell is more disadvantageous than advantageous and i cast remove curse on it does it break owner's attunement to the object because it doesn't state in the "cursed" weapon's (Berserker greataxe's) statistics that it's cursed. Or if a Wererat has bite a member of the party and the bitten character doesn't succeed on the sawing throw and is affected can someone cast remove curse on him to remove the effect?

Do these situations count as a "curse" so it can be removed or does it have to state that it's a "curse" so it can be removed?

The spell remove curse only states:

At your touch, all curses affecting one creature or object end. If the object is a cursed magic item, its curse remains, but the spell breaks its owner’s attunement to the object so it can be removed or discarded.

What is considered "cursed"?

If a spell has been cast on a weapon and the spell is more disadvantageous than advantageous and I cast remove curse on it, does it break the owner's attunement to the object? Because it doesn't state in the "cursed" weapon's (Berserker greataxe's) statistics that it's cursed.

Or if a Wererat has bitten a member of the party, and the bitten character doesn't succeed on the sawing throw and is affected, can someone cast remove curse on him to remove the effect?

Do these situations count as a "curse" so it can be removed by the spell, or does it have to state that it's a "curse" in order to be removed by the spell?