Lackadaisical

An adjective used to describe someone as lethargic or listless, which dates from the late 18th century. This in turn derives from a much earlier expression ‘alack a day’, which was a common expression in the 15th century, where alack is the old form of alas and thus ‘alack a day” meant alas the day or alas what a day. From the late 18th century, lackadaisical had become the adjective that developed from alack a day and described a person who is apt to go around crying, ‘alack a day’ or ‘lack a day’ and, as the OED puts it, is “full of vapid feeling or sentiment; affectedly languishing”. See Alas.