substitute

The word "substitute" has several meanings, all revolving around the idea of replacing one thing with another. Most commonly, it refers to someone or something that takes the place of another, either temporarily or sometimes more permanently. Think of a substitute teacher stepping in for a regular classroom instructor, or a relief pitcher entering a baseball game. In these cases, the substitute performs the same function as the original but is not necessarily the first choice.

However, "substitute" can also describe an alternative to something else entirely. A sugar substitute like stevia is used instead of sugar, offering a different way to sweeten your food. Similarly, you might find a substitute ingredient in a recipe if you're missing one - applesauce can be a substitute for oil in baking.

The context usually makes it clear which meaning is intended. In legal terms, "substituted service" means delivering court papers in a different way than originally planned when the standard method is impossible. In chemistry, a "substitution reaction" involves replacing one atom or group of atoms with another within a molecule.

So whether it's filling a role, offering an alternative, or changing the composition of something, to substitute is to replace, providing a stand-in when the original is not available or suitable.