As a Noun: 1. The idea or feeling that something is true. English = belief. 2. A strong belief that something is true. English = conviction. 3. A set of beliefs, principles, or opinions that strongly influence the way people live or work. English = creed. As a Verb or Adjective: 1. To think that something is true. English = believe. 2. To strongly believe that something is true. English = (be) convinced of.