1: a doctrine that this world is the best possible world
2: an inclination to put the most favorable construction upon actions and events or to anticipate the best possible outcome
That is the Merriam-Webster definition of a trait that I feel is underrated. And before you leave because I sound like a positive attitude hippie, give me a moment of your time. Think about starting a new hobby – anything (e.g. blogging, vlogging, drawing, painting, skateboarding, stargazing etc.). Now think about not only starting that hobby, but doing so publicly. For most, or at least for me, that is a scary thought for a multitude of reasons. But people who are heavily optimistic react differently.