decide is a verb, decisive is an adjective, decision is a noun:He can't decide what to eat for breakfast. He's not very decisive when he needs to take action. He made a decision about what to eat for breakfast.
to solve or conclude (a question, controversy, or struggle) by giving victory to one side:The judge decided the case in favor of the plaintiff.
to determine or settle (something in dispute or doubt):to decide an argument.
to bring (a person) to a decision; persuade or convince:The new evidence decided him.
to settle something in dispute or doubt:The judge decided in favor of the plaintiff.
to make a judgment or determine a preference; come to a conclusion.
Latin dēcīdere literally, to cut off, equivalent. to dē-de- + -cīdere (combining form of caedere to cut)
Middle French decider
Middle English deciden 1350–1400
1.See corresponding entry in UnabridgedDecide,resolve,determine imply settling upon a purpose and being able to adhere to it. To decide is to make up one's mind as to what shall be done and the way to do it:He decided to go today.To resolve is to show firmness of purpose:He resolved to ask for a promotion.To determine is to make up one's mind and then to stick to a fixed or settled purpose:determined to maintain his position at all costs.