'dreamless' originates from the Old English word 'drēam', meaning 'joy' or 'music', combined with the suffix '-less', indicating absence.

'drēam' transformed into the Middle English word 'dreem', and eventually became the modern English word 'dream'.

Initially, 'drēam' meant 'joy' or 'music', but over time it evolved into its current meaning of 'a series of thoughts, images, or emotions occurring during sleep'.