The term British Snake refers to two species of venomous snakes found in the United Kingdom, the ADDER and the VIPER. The ADDER (5 letters) is the only venomous snake native to the UK and is found throughout England, Scotland, Wales, and Ireland. The VIPER (5 letters) is a non-native species that was introduced to the UK in the early 20th century and is now found in parts of England and Wales. Both species are considered dangerous and should be avoided.