1. of the greatest importance; fundamental

1. a high-ranking official in the Roman Catholic Church
2. a bright red North American songbird
3. a whole number used in counting
Usage: mathematics

Examples

• The cardinal rule of safety is to always wear your seatbelt.
• Honesty is a cardinal virtue in any relationship.
• The cardinal blessed the congregation during the ceremony.
• A bright red cardinal perched on the snowy branch.
• Cardinals are common backyard birds in eastern North America.
• The number five is a cardinal number, not an ordinal.
• She made a cardinal error by forgetting to save her work.
• The cardinal principles of democracy include freedom and equality.