dim ‧ i ‧ nu ‧ tion AC /ˌdɪməˈnjuːʃ ə n, ˌdɪmɪˈnjuːʃ ə n $ -ˈnuː-/ BrE AmE noun [uncountable and countable] formal
[ Date: 1300-1400 ; Language: Old French ; Origin: Latin minuere 'to make less' ]
a reduction in the size, number, or amount of something
diminution of/in
a diminution in value