Thick-billed Flowerpecker ( Dicaeum agile) is about 10 cm long and has a dark stout beak and short tail. dull greyish with diffuse streaking on the light buffy underparts and darker grey brown above. The rump is slightly more olive in the nominate race. The bill is dark, somewhat stout and heavy and the iris is reddish. The sexes are not distinguishable in the field , The juvenile has a paler base to the mandible and less streaks on the underside. There are whitish spots at the tip of the tail feathers.
The nest has been described as appearing camouflaged like a dry leaf. It is a pendant purse like structure made of cobwebs or fine plant fibres and is located from 3 to 15 metres high suspended from a thin horizontal branch.
The breeding season is December to March. Both male and female participate in nest building. The usual clutch is about 3 eggs but can vary from 2 to 4.The incubation period is around 13 days and the chick takes around 18 days to fledge