'ashling' originates from Irish Gaelic, specifically the word 'aisling', where 'aisling' meant 'vision' or 'dream'. It is also analyzable in English as 'ash' + the diminutive suffix '-ling' (from Old English roots) meaning 'small' or 'young'.

'ashling' developed as an anglicized spelling of the Irish Gaelic name 'aisling' and came into English usage as a given name; separately, English formation from Old English 'æsc' ('ash') plus '-ling' produced a rare noun meaning 'young ash tree'.

Initially it meant 'vision' or 'dream' in Irish (as 'aisling'), while the English-formative sense originally meant 'small/young ash'; over time the anglicized form became used primarily as a given name with the 'vision/dream' sense, and the 'young ash' sense remains rare.