1. something that is needed or required; an essential thing
2. the condition of being necessary or unavoidable
3. urgent need or poverty that forces action

Examples

• Food and water are basic necessities for survival.
• The necessity of wearing a helmet while biking cannot be overstated.
• Out of necessity, she learned to cook when she moved out.
• The broken bridge made taking the long route a necessity.
• Economic necessity forced many families to move to cheaper areas.
• Is a car really a necessity in this city, or just a convenience?
• The necessity of the situation required immediate action.