When something is really 'Classy', , we say it is 'posh'. What is the origin of the word "Posh"?

Question

A restaurant or even a colony may be called 'posh'.

Answer 1

WORD HISTORY “Oh yes, Mater, we had a posh time of it down there.” So in Punch for September 25, 1918, do we find the first recorded instance posh, meaning “smart and fashionable.” A popular theory holds that it is derived from the initials of “Port Out, Starboard Home,” the cooler, and thus more expensive, side of ships traveling between England and India in the mid-19th century. The acronym POSH was supposedly stamped on the tickets of first-class passengers traveling on that side of ships owned by the Peninsular and Oriental Steam Navigation Company. No known evidence supports this theory, however. Another word posh was 19th- and early 20th-century British slang for “money,” specifically “a halfpenny, cash of small value.” This word is borrowed from the Romany word påšh, “half,” which was used in combinations such as påšhera, “halfpenny.” Posh, also meaning “a dandy,” is recorded in two dictionaries of slang, published in 1890 and 1902, although this particular posh may be still another word. This word or these words are, however, much more likely to be the source of posh than “Port Out, Starboard Home,” although the latter source certainly has caught the public's etymological fancy.

Answer 2

The origin is unknown. There is a theory that says it originally stood for "port out, starboard home," indicating the most desirable accommodations on a steamship from England to India (sun in the morning and shade in the afternoon).

There's also a theory that it is some kind of turn-of-the-century university slang meaning "swish."

Another theory says it's a turn-of-the-century word meaning "a dandy." Webster's indicates that none of these theories have enough backing evidence to say that one is correct over another.