'daydream' originates from the combination of 'day' and 'dream', where 'day' refers to the time of light and 'dream' refers to a series of thoughts, images, or emotions occurring during sleep.

'daydream' evolved from the Old English word 'drēam', which meant 'joy' or 'music', and eventually became associated with the modern concept of dreaming while awake.

Initially, it meant 'joyful thoughts', but over time it evolved into its current meaning of 'pleasant thoughts that distract from reality'.