1. the quality or state of being flat or level
2. lack of variation, interest, or excitement; dullness
3. lack of depth or dimension in sound, color, or emotion

Examples

• The flatness of the prairie stretched endlessly to the horizon.
• We checked the flatness of the table before setting up the equipment.
• The flatness of his voice revealed his disappointment.
• The painting’s flatness made it look two-dimensional.
• She complained about the flatness of the soda after it sat open all day.
• The flatness of the performance disappointed the audience.
• The road’s flatness made it perfect for cycling.