infimum
Concise Oxford English Dictionary © 2008 Oxford University Press:
infimum /ɪnˈfʌɪməm/
▶noun Mathematics the largest quantity that is less than or equal to each of a given set or subset of quantities. The opposite of supremum.
– origin 1940s: from L., lit. ‘lowest part’.
'infimum' also found in these Oxford entries:

