Howdy is an informal salutation in the English language often used in the Southern United States. Originally a shortened form of the inquiry How do ye?, it was first used in Southern England in the 18th century. Etymology. The word derives from the phrase "How do ye?," which was used in late 16th century England to ask about others' health. The phrase saw increasing degrees of dialectal contraction over time, first being contracted to "how dee," then to "howdy'ee," and finally to its modern form. Despite the etymology of the term, its modern usage is as a greeting and not as an inquiry.
https://en.wikipedia.org/wiki/Howdy