While reading some discussions here, I've noticed that some people thought trading is part of gambling.

IMO, to be specific, when we're trading, it should be a risk. Risk means, you have considered the possible effects of your decisions and you can predict the movements in the market.

Gambling is more on guessing, we don't have control over the possible outcome. Obviously, guessing can't be applied in trading, it'll just give you a huge loss. So definitely, based on the definition, the term we should adapt is risk.