Associated with the upper classes. / Stylish, elegant, exclusive (expensive).

An exclamation expressing derision.

fragments produced by an impact / slush

(normally in the phrasal verb posh up) To make posh, or posher.

(physics) The antimatter equivalent of an electron, having the same mass but a positive charge

(motor racing) The bottom qualifying position in a race, on the outside of the last row at the starting line.

(motor racing) The position given at the start of a race, ranked from most favorable to least favorable, awarded according to the times achieved during qualification.

(motor racing) The top qualifying position for a race, on the inside of the front row at the starting line. / (by extension) First place.

(modifying a clause or predicate) Perhaps; indicates that the proposition may be true (is not certainly false) regardless of any facts or circumstances known to, stated by or implied by the speaker.

(usually not comparable) Able but not certain to happen; neither inevitable nor impossible. / (comparable) Capable of being done or achieved; feasible. / Being considered, e.g. for a position.