'ashier' originates from English, specifically the adjective 'ashy' (from 'ash' + suffix '-y'), with the comparative suffix '-er' added to form 'ashier'.

'ash' comes from Old English 'æsce' (also spelled 'æsc'), from Proto-Germanic '*askjaz'. 'ashy' was formed in English by adding '-y' to 'ash', and 'ashier' developed by adding the comparative suffix '-er' to 'ashy'.

Initially related to 'ash' (the residue of burning) or 'ash-colored'; over time it kept the sense of 'having the quality of ash' and now 'ashier' specifically means 'more ash-like' (paler or more covered with ash).