This word [ 'posh' ] is only used in casual speaking. It is most often used ironically to draw attention to the 'status' of something or someone - 'Why are you acting so posh today ? ', 'She fancies herself as posh', 'Let's go for some posh nosh' [a fancy/classy meal/food]. . . . . It is said to originate from the days of sea travel from England to India, China, Australia and the East, when the better side of a ship to have your berth was 'Port [on the way] Out, Starboard [on the way] Home' - 'port' and 'starboard' refer to the two sides of a ship.

'Posh' is relatively unique to the United Kingdom (and perhaps Ireland) in that it is related to the UK class system, and refers to the upper classes and aristocracy. It is most frequenty used negatively; you don't want to be called posh. Used by people who consider themselves below the upper classes (ie. most people), sometimes against people who are perceived as trying to 'climb above their station', or just against literal upper classes who are not generally perceived well by regular folk. More positive synonyms might be 'classy', 'sophisticated', 'elegant', 'upmarket', 'luxury' 'well-to-do'. Walter By the way - I am recruiting new students for the new year! Special discount rates for January! :)