"We’re too enthusiastic about the lexicon to be lackadaisical about words, but lackadaisical itself is rooted in the sort of sorrow that can put a damper on one’s passion for vocabulary expansion. When folks living from the late 17th to the late 19th century had one of those days when nothing goes right, they could cry "Lackaday!" to express their sorrow and disappointment as a shortened form of the expression "alack the day." (Alack is an interjection used to express sorrow or regret.) By the mid-1700s, the adjective lackadaisical had been formed to describe these miserable ones and their doings and sayings. Around the same time, the word lackadaisy was introduced to the language as an interjection similar to lackaday; it was never as prevalent as lackaday, but it may have influenced the development of lackadaisical."