1. most lacking in kindness, compassion, or consideration; most harsh or cruel
Usage: superlative form of unkindly

Examples

• That was the unkindliest remark she had ever made to her sister.
• The critic’s unkindliest review destroyed the young author’s confidence.
• Even in his unkindliest moments, he never resorted to personal attacks.
• The weather turned its unkindliest face toward the travelers.
• Her unkindliest words came when she was most frustrated.
• The unkindliest cut of all was his betrayal of their friendship.