'coalless' originates from Modern English, specifically the word 'coal' combined with the suffix '-less', where 'coal' meant 'fossil fuel formed from carbonized plant matter' and '-less' meant 'without'.

'coal' comes from Old English 'col' (meaning coal or charcoal) and the suffix '-less' derives from Old English '-lēas'; the compound formation like 'coal-less' is a Modern English creation producing 'coalless'.

Initially it meant 'without coal', and over time it has retained that core meaning as an adjective describing absence of coal.