1. the quality of being simple, unadorned, or without decoration
2. the quality of being clear and easy to understand
3. the quality of being unattractive or lacking in beauty

Examples

• The plainness of the room made it feel cold and unwelcoming.
• She appreciated the plainness of his speech and direct manner.
• The building’s plainness contrasted sharply with the ornate cathedral nearby.
• Despite her plainness, she had a warm and engaging personality.
• The plainness of the instructions made them easy to follow.
• He preferred the plainness of country living to city sophistication.
• The plainness of her dress reflected her modest lifestyle.