File:Giant Hornbill Buceros bicornis Valparai Tamil Nadu India.jpg

The Great Hornbill is a large bird, 95–130 cm (37–51 in) long, with a 152 cm (60 in) wingspan and a weight of 2.15–4 kg (4.7-8.8 lbs). It is the heaviest, but not the longest, Asian hornbill. The most prominent feature of the hornbill is the bright yellow and black casque on top of its massive bill. The casque appears U-shaped when viewed from the front and the top is concave with two ridges along the sides that form points in the front, a reference to which is made in the Latin species epithet bicornis. The casque is hollow and serves no known purpose although they are believed to be the result of sexual selection. Male hornbills have been known to indulge in aerial casque butting, with birds striking each other in flight.

Females are smaller than males and have bluish-white instead of red eyes although the orbital skin is pinkish. Like other hornbills, they have prominent "eyelashes". The back of the casque is reddish in females while the underside of the front and back of the casque is black in males. The male spreads the preen gland secretion which is yellow onto the primaries and bill to give them the bright yellow colour.The commissure of the beak is black and has a serrated and worn edge with age.