The term 'greatest lower bound' of a subset A of real number R is also called .............  (NB: Answer should be lower case)

The term 'greatest lower bound' of a subset $A$ of real numbers $\mathbb{R}$ is also called infimum.

The infimum of a subset is the largest number that is less than or equal to every number in that subset. It can be thought of as the "best" lower bound. For instance, if the subset includes numbers that approach a limit, the infimum provides a way to express this limit as the lower boundary, even if that limit isn’t included in the subset itself. It's important to note that while every non-empty set of real numbers that is bounded below has an infimum, it may or may not be a member of the set. Understanding the concept of infimum is crucial in fields like calculus and real analysis, particularly in the study of convergence and limits.