Beak/biːk/ Definition 1 of 3Pro Tip 1/3Bird Anatomy Relates to the physical structure of birds, often mentioned in biology. An eagle's beak is adapted for tearing its prey. Pro Tip 2/3Birds' Diet Link The shape of a bird's beak indicates its diet and feeding habits. A hummingbird’s tiny beak is perfect for sipping nectar. Pro Tip 3/3Beak in Idioms Used metaphorically in phrases to suggest nosiness or intrusion. Keep your beak out of my business!