n. 1. (Logic) a function that associates specific elements of a domain with each free variable in a formal calculus. Compare interpretation. See also model, valuation. 2. (Computing) a statement in a program that allocates a value to a variable, usually written as in
x := y + z.
If the new value is a function of the previous value of that same variable this notation is still used; thus
x : = x + 1
is an instruction to increase the value of x by one.