What is the X in X-mas?
short for gentleman, by 17c. (in early uses it is difficult to distinguish the shortening from the common abbreviation gent.). "Early in the nineteenth century the word was colloquial and slightly jocular; about 1840 its use came to be regarded as a mark of low breeding" [OED].
A man; fellow; guy: A hefty, tough-talking gent of not quite 50 (1564+)