What is the X in X-mas?
allusive use dates to 1838, from Baron Frankenstein (German, "free stone"), character in Mary Shelley's 1818 novel "Frankenstein: The Modern Prometheus." Commonly used, mistakenly, as the proper name of the monster he created, and thus franken- extended 1990s as a prefix to mean "non-natural."
(1818) A novel by Mary Wollstonecraft Shelley. The title character, Dr. Victor Frankenstein, makes a manlike monster from parts of cadavers and brings it to life by the power of an electrical charge. Frankenstein's monster is larger than most men and fantastically strong.
Note: Frequently the subject of horror films, the monster is usually pictured with an oversized square brow, metal bolts in his neck and forehead, and greenish skin. People often mistakenly refer to the monster, rather than to his creator, as “Frankenstein.”