at ‧ tri ‧ tion /əˈtrɪʃ ə n/ BrE AmE noun [uncountable] formal
[ Date: 1400-1500 ; Language: Latin ; Origin: attritio , from atterere 'to rub against' , from ad- 'to' + terere 'to rub' ]
1 . the process of gradually destroying your enemy or making them weak by attacking them continuously:
a war of attrition
2 . especially American English when people leave a company or course of study and are not replaced:
Staff reductions could be achieved through attrition and early retirements.