Here's a few of my current favourites from a range of manufactures.
Dry relates to the overall lane condition which has broken down through usage and has lost much of its original oil. This depletion requires the bowler to select a ball that will not 'read' the lane till it progresses further, thus conserving energy and strike power.
Mid typically describes the league patterns found in most centres, not too wet, not too dry with a receptive back end to allow the ball to skid then grip and turn in strongly towards the strike (1/3 pin) pocket.
Wet lane conditions usually refer to tournament patterns when liberal amounts of oil are applied to the first 20 feet of the lane, creating much earlier skid.
'Polys' are straight balls, which are great for beginners or as spare balls. They come in all sorts of colours and designs, so why not pop in and see what else is in stock.