It is mostly the rattlesnake.
Pine woods snake, Plain Bellied water snake, plains garter snake and Pygmy Rattlesnakes
Consider the Adder, commonly called the: Death Adder(Acanthophis antarcticus) or the Australian Brown Snake (Pseudonaja textilis).
"Poisonous" is an adjective as it is used to describe a noun (ie. The poisonous snake slithered away after it had bitten its victim).
No snake is poisonous, though some are venomous. Garter snakes are technically very mildly venomous, but this venom is harmless to humans.
The first snake that came to mind when I read the question was... Mamba.
A rattlesnake.
The aptly named 'Brown Snake' from Australia is a venomous brown snake.
The 3-letter poisonous snake is almost always "asp."
rattle snake
Asps (plural) http://en.wikipedia.org/wiki/Asp_(reptile)
Rattle snake
western rattle snake
Most poisonous snake have fang.
the most poisonous is the beaked sea snake
asp, a snake. Cleopatra committed suicide by giving herself a poisonous snake bit.
Sidewinder
rattle snake