'alackaday' originates from Middle English, specifically the phrase 'alack the day,' where 'alack' was an expression of regret and 'the day' referred to the time or occasion.

'alack the day' transformed into the more concise 'alackaday' in modern English usage.

Initially, it meant 'regret for the day or occasion,' but over time it evolved into a general expression of sorrow or dismay.