As a matter of adopting sensible definitions, I think you need to draw the line somewhere between what is gambling and what is not.
If the risk taken can, in principle, be shifted in your favour (i.e. to produce positive expectation) through application of skill, then it isn't gambling. For example, in my mind, betting on whether you will win a game of chess is not gambling. On the other hand, if you cannot influence the outcome in your favour through skill, then it is gambling. Roulette is generally a good example of this (with the caveat that in some very specific circumstances it's possible to beat with skill).
If we're limiting the definition to merely risk-taking (you might win or you might lose) without factoring in skill, then virtually everything in life becomes gambling. For example, you gamble when you deposit money in the bank because it might go bust.
There's also the legal definition, in which case it's just a matter of checking whether the jurisdiction you are in considers the activity to be gambling or not.
If the risk taken can, in principle, be shifted in your favour (i.e. to produce positive expectation) through application of skill, then it isn't gambling. For example, in my mind, betting on whether you will win a game of chess is not gambling. On the other hand, if you cannot influence the outcome in your favour through skill, then it is gambling. Roulette is generally a good example of this (with the caveat that in some very specific circumstances it's possible to beat with skill).
If we're limiting the definition to merely risk-taking (you might win or you might lose) without factoring in skill, then virtually everything in life becomes gambling. For example, you gamble when you deposit money in the bank because it might go bust.
There's also the legal definition, in which case it's just a matter of checking whether the jurisdiction you are in considers the activity to be gambling or not.