The term 'ANCIENT ADDER' is a combination of two words, 'ANCIENT' and 'ADDER'. ANCIENT refers to something that is very old, while ADDER is a type of snake found in Europe and Asia. The crossword solution for this term is 'ABACUS', which is an ANCIENT counting device used in many cultures. It consists of a frame with beads or other objects that can be moved along rods or strings to perform calculations. ABACUS was used in ANCIENT times to help people with basic arithmetic operations such as addition, subtraction, multiplication, and division.