What is the X in X-mas?
"philanderer," from the legendary dissolute Spanish nobleman whose rakish exploits formed the stuff of popular tales in Spain from early 17c., dramatized by Gabriel Tellez in "Convivado de Piedra." Adapted into French and Italian before 1700; Used attributively in English for "ladies' man, womanizer" from the time of Byron's popular poem about him (1819).
Don Juan (dŏn wŏn')
A man who is an obsessive seducer of women, especially one who does so out of feelings of impotence or inferiority.
An obsessive and unscrupulous pursuer of women: “He charms all his female colleagues; he is the Don Juan of the office.” From the legendary nobleman who seduced hundreds of women and was eventually damned for his immoral ways.
A legendary Spanish nobleman and chaser of women; he first appears in Spanish literature in the seventeenth century. Many authors and composers have depicted him: Wolfgang Amadeus Mozart, in the opera Don Giovanni; Lord Byron, in the long poem “Don Juan”; and George Bernard Shaw, in the play Man and Superman.
A man who has great sexual success with a large number of women
[1848+; fr the name of a legendary dissolute Spanish nobleman, popularized in Britain by Byron's poem Don Juan]