As a Noun: 1. A choice that you make about what should be done or about which is the best of various alternatives. English = decision. 2. The act of deciding something. English = decision, decision making. As a Verb or Adjective: 1. To choose to do something, usually after you have thought carefully about the other possibilities. English = decide. 2. To consider a number of different possibilities and their importance in relation to each other in order to help you make a decision. Idiomatic English = weigh up.