Grounding a variable - first-order logic:
The perform of making ourselves clear about a variable by introducing an exists or a forall sign is called quantifying the variable. That can exists and for all sign are likewise calling quantifiers in first-order logic.
Replacement a ground term for a variable is oftenly called as "grounding a variable", "applying a substitution" and "performing an instantiation". According to an example of instantiation is: turning the sentence "All meals are five pounds" in "Spaghetti is five pounds" - we have notice that grounded the value such of the variable meal to the constant spaghetti to grant us an instance of the sentence.