As a Noun: 1. The fact that something is not complicated but is easily understood or easily done. English = simplicity. 2. A person who has very low intelligence. English = simpleton. As a Verb or Adjective: 1. To be not complicated; to be easy to understand or to do. English = (be) simple, (be) easy. 2. To make something easier to understand or do. English = simplify. 3. In mathematics, to re-write an expression, fraction, or problem in a simpler form. It makes the problem easy with calculations and solving. English = simplify. As Modifier: 1. Used at the beginning of a sentence to mean that you are about to say something as briefly and as clearly as possible. English = simply, briefly. 2. Used next to a verb to mean that the action is the only action someone does and is not something more complicated as someone else may have claimed. English = simply, only, just.