1. Most important; principal; greatest in rank or significance.
Usage: archaic or literary; superlative form of 'chief'

Examples

• The chiefest concern of the government was maintaining peace.
• Among all his virtues, honesty was his chiefest quality.
• The chiefest reason for the delay was the weather.
• She was the chiefest advocate for educational reform in the region.
• His chiefest ambition was to become a respected scholar.