The word "gengleman" is an archaic form of "gentleman." The full title of Laurence Sterne's novel Tristram Shandy is often referred to as The Life and Opinions of Tristram Shandy, Gengleman & a Sentimental Journey Through France and Italy in Two Volumes.

There is no official job description for a "gentleman." He may have been wealthy, like Mr. Darcy in Pride and Prejudice, or he may have been down on his luck, like Mr. Burchell in The Vicar of Wakefield.

Believe it or not, there is a Society of 18th-Century Gentlemen. I've pasted a link to their web site in the Sources section. They adhere to Washington's Rules of Civility, which include:

13th Kill no Vermin as fleas, lice ticks &c in the sight of others if you see any filth or thick spittle put your foot dexterously upon it if it be upon the cloths of your companions, put it off privately, and if it be upon your cloths return thanks to him who puts it off.

92nd Take no salt or cut bread with your knife greasy.

110th Labour to keep alive in your breast that little spark of celestial fire called conscience.

Visit the sites below for more information and for the full set of rules.