The term "Atheistick" can be traced back to the 16th century and has its roots in the Greek language. The word "atheist" comes from the Greek words "a-" (meaning "without" or "not") and "theos" (meaning "god"). The addition of the suffix "-ick" was influenced by the French language, where it was commonly used to create adjectives. In this case, it was used to describe someone or something as "atheistic" or "pertaining to atheism". Over time, "atheistick" evolved into the modern English term "atheistic" with a standardized spelling.