Betting odds are represented by X and Y, which are both numbers. Most often, the word to is represented by slashes or hyphens or colons. So when people say 5/2, that’s the same as saying “five to two”. Let’s take a closer look at the basics then, shall we?
Odds against refers to situations wherein the chances that something will not happen is higher than the chances that it will happen. For example, if the odds are five to two, or 5/2, or 5/2 against, then in gambling the amount the gambler will win will be bigger than the amount that was bet.
Odds on is the opposite of odds against. Sometimes it’s written with the smaller number first, but more often, it’s used with the word on. So if it’s “4/2 on”, then it’s been determined that something is twice as likely to happen. There is still a profit for the gambler if he or she wins.
Even odds basically means that the chances for something to happen is the same as the chances of it not happening. It’s what is most commonly referred to as a 50-50 chance. The best example for this is a coin toss, wherein people guess on heads or tails. In the gambling context, people who win in an even odds bet double their stake.