A goal or aim that one is trying to achieve. Her main objective is to complete the project by the end of the month.
A thing aimed at or sought; a target. The objective of the mission was to gather intelligence on enemy movements.
The lens or system of lenses in a microscope or telescope that is nearest to the object being viewed. The scientist adjusted the objective to get a clearer view of the specimen.
(Grammar) The objective case. In 'She helped him', 'him' is in the objective.