1. a smooth wavelike motion or form; a gentle rising and falling movement
2. a wavy form, outline, or surface

Examples

• The undulation of the wheat field in the breeze was mesmerizing.
• We could see the gentle undulation of the hills in the distance.
• The snake moved with a smooth undulation across the sand.
• The undulation of the ocean waves created a rhythmic pattern.
• The fabric showed a beautiful undulation when draped over the chair.
• The undulation of her voice made the song particularly haunting.