A type of leaf, found in ferns and some higher plants, which is usually large and has a complex vascular system with leaf gaps in the stem stele. Opposed to microphyll.
In the Raunkiaer system of leaf-size classification: a very large leaf with a surface area greater than 1640 square centimetres.
Early 20th century; earliest use found in New Phytologist. From mega- + -phyll, in sense 2 after Danish megafyl.