proof

Proof isn't just for math class. It's what you show when you want to make it clear that something is true or real. It might be a logical argument in mathematics, a set of facts in court, or a receipt that shows you paid for something. You can also use it in everyday life, as in proof of identity or proof of address. Sometimes "proof" means a test version, such as a printed copy or photo checked before the final version. It also appears in words like "waterproof," where it means protected against something.

The word "proof" carries a lot of weight. At its core, it means evidence or a clear argument that shows something is true, real, or valid. This is most familiar in mathematics, where a proof is a step-by-step logical argument showing that a statement follows from accepted rules and ideas. In that setting, a proof is meant to settle the question completely.

However, "proof" extends far beyond numbers and equations. In legal contexts, it refers to evidence used to support a case or show that a claim is true. More generally, "proof" can be anything that strongly supports what someone is saying. You might say, "This receipt is proof that I paid for the item," or "Her actions are proof of her dedication." In everyday use, it often points to something that removes doubt or gives strong reason to believe.

The word also has specialized meanings. In printing and photography, a "proof" is a test version of an image or text checked before final production. It lets you catch mistakes before the finished version is made. In baking, to "proof" dough means to let it rise. In the world of spirits, "proof" is a measure of alcohol strength. And in words like "bulletproof" or "waterproof," it shows protection or resistance. Whether it is a logical argument, a piece of evidence, a test version, or part of a word about protection, "proof" is connected to showing that something holds up under checking.