Omni is a prefix (a word part added to the beginning of other words) that means “all” or “every.” It comes from Latin and transforms words to indicate something total or unlimited.

When you see omni at the start of a word, you know you're dealing with something comprehensive or universal. An omnivore eats all types of food, both plants and meat (unlike an herbivore, which eats only plants, or a carnivore, which eats only meat). An omniscient narrator in a story knows everything about all the characters, even their private thoughts. Someone omnipotent has unlimited power.

You'll find this prefix in everyday words and in more specialized vocabulary. An omnibus bill in Congress includes many different laws bundled together. The word omnibus originally referred to a large vehicle that carried all types of passengers, which eventually shortened to just “bus.”

When you encounter a new word starting with omni, you've got a head start on figuring out its meaning. The prefix signals totality, completeness, or unlimited scope. It's like a little flag waving at the beginning of the word saying, “this is about everything” or “this covers all possibilities.”