The suffix -ity turns adjectives into nouns that name qualities or states of being. When you add -ity to an adjective, you create a word for that characteristic itself.

Think about the word curious. Add -ity and you get curiosity, the quality of being curious. Generous becomes generosity, the quality of being generous. Dense becomes density, the measure of how dense something is.

This suffix appears everywhere in English. Complexity names the quality of being complex. Velocity describes the state of moving at a certain speed. Creativity captures the quality of being creative. The word electricity comes from electric, naming that invisible force that powers your lights and computer.

Sometimes the spelling changes slightly when you add -ity. Able becomes ability. Authentic becomes authenticity. But the pattern stays the same: you're turning a describing word into a naming word.

When you understand -ity, you can figure out hundreds of words. See absurdity? You know it means the quality of being absurd. Spot humidity? It's the quality of being humid. This little suffix is one of the most productive tools in English, helping us name every quality and state we encounter.