Merriam-Webster

A person of great wealth or prominence

Wikipedia

…can also be used metaphorically for people who have a grandiose style or manner…

Free Dictionary

One who returns to Europe from the East with immense riches: hence, any man of great wealth. “A bilious old nabob.” –Macaulay.

The head. (See nob)

–From the 1811 Dictionary of the Vulgar Tongue.

More hog than gentleman. A saying of any low pretender to precedency.

–From the 1811 Dictionary of the Vulgar Tongue.

A great eater.

–From the 1811 Dictionary of the Vulgar Tongue.