There are a lot of betting terms to master, and understanding, here you can find the general online betting terms out there:
Odds: Also referred to as the price. The returns a bookmaker offers for a selection to win.
Odds On: Refers to a price where the odds are less than evens (fractional) or 2 (decimal).
Odds Against: Refers to a price where the odds are greater than evens (fractional) or 2 (decimal).
On the Bit: When a horse needs no riding from the jockey
On the Nose: A bet on a horse to win
Outsider: The opposite of a favourite.
Over-round: The margin the bookmaker builds into their odds to ensure they make a profit on an event.
Overweight: An eventuality where the jockey weighs more than the weight one of his rides is supposed to carry.