Small terrestrial viper common in northern Eurasia; SYN. common viper, Vipera berus.
(snake) European venomous snake, the common viper Vipera berus. Growing to about 60 cm/24 in in length, it has a thick body, triangular head, a characteristic V-shaped mark on its head and, often, zigzag markings along the back. It feeds on small mammals and lizards. The puff adder Bitis arietans is a large, yellowish, thick-bodied viper up to 1.6 m/5 ft long, living in Africa and Arabia.

(circuit) Electronic circuit in a computer or calculator that carries out the process of adding two binary numbers. A separate adder is needed for each pair of binary bits to be added. Such circuits are essential components of a computer's arithmetic and logic unit (ALU).
1. A component of the CPU (central processing unit) that adds two numbers sent to it by processing instructions. See also central processing unit.
2. A circuit that sums the amplitudes, or strength, of two input signals. See also full adder, half adder.