U

unary expression:An expression consisting of a single operand preceded or followed by a unary operator.

unary operator:An operator that takes a single operand.

unlinked dialog box :A dialog box that is called from the program. The call is based on user action rather than the menu.

unresolved reference:A reference to a global or external variable or function that cannot be found, either in the modules being linked or in the libraries that are linked with those modules.