a person who adds numbers
"The teacher called on the adder to solve the final multiplication problem before dismissing class."
a machine that adds numbers
"The engineer used an adder to quickly sum up all the sensor readings from the experiment."
small terrestrial viper common in northern Eurasia
"Hikers often carry a flashlight when walking at night to spot the adder hiding along the rocky edges of the moorland."
Any snake.
"The old mechanical adder whirred loudly as it calculated the total cost of all fifty items on the receipt."
Someone who or something which performs arithmetic addition; a machine for adding numbers.