'customarily-maintained' originates from the combination of 'customarily' and 'maintained'. 'Customarily' comes from 'custom', which originates from Latin 'consuetudo', meaning 'habit or usage'. 'Maintained' comes from Old French 'maintenir', meaning 'to hold in hand'.

'customarily' evolved from the Latin 'consuetudo' through Old French 'costume', while 'maintained' evolved from Old French 'maintenir'.

Initially, 'customarily' meant 'according to custom', and 'maintained' meant 'to hold in hand'. Over time, they combined to describe something kept in good order by tradition.