An argument or statement can be deniable if someone else says it's not true and there's no proof to back it up.
When people discuss politics or news, they might say something is "deniable" because it sounds suspicious. This means that some other person or group could easily deny what was said and claim it's a lie. For example, if a politician makes a strong accusation against their opponent but then says the details are "deniable," they're trying to make it seem like the accusation isn't solid fact. It's like saying there's no way to prove something is true, so why believe it?
Able to be denied or contradicted.
