adj. & adv. colloq.
adj. 1 smart; stylish. 2 of or associated with the upper classes (spoke with a posh accent).
adv. in a stylish or upper-class way (talk posh; act posh). posh up smarten up. poshly adv. poshness n.
[ 20th c.: perh. f. sl. posh a dandy: port out starboard home (referring to the more comfortable accommodation on ships to and from the East) is a later association and not the true origin ]