As a Noun: 1. The study of the nature and behaviour of natural things and the knowledge that we obtain about them. English = science. 2. An expert who does work in one of the sciences. English = scientist. As a Verb or Adjective: 1. To relate to science or to a particular science. English = (be) scientific. 2. To do something in a systematic way, using experiments and tests. English = (be) scientific.