How do you define bluff in poker?

You can only detect a bluff when your opponent opens his cards, you just need to monitor your opponent’s play and write down notes

I think of it like this: If you think you are ahead 51% of the time or more and make a bet then it’s a value bet. If you think you are behind then it’s a bluff. As others have mentioned sometimes you don’t even know your hand was a bluff until you see villains hand.

I think and I always say, bluffing is an art that is learned through skill and time. It is not something that can be learned with certainty from another player but rather it is something that is developed over time at the gaming table. It is very important to know how much you are going to bet, your number of chips and who you are going to bluff against, because it is always better to do it against the weakest player at the table than against the strongest. Regards.

It's a question of cost benefit
If it could cost you your tournament, it's not a good idea