Ordinal numbers show the position of something compared to other objects. For example:

I came third (3rd) in the cooking contest. There were a total of 12 people in the competion and I was placed at number 3.

An easy way to remember the difference between the two is:

ordinal = order​

​idioms with ordinal numbers

Here are the most common idioms that contain ordinal numbers.

ordinal number idioms
ordinal number idioms - cast the first stone
ordinal number idioms - draw first blood
ordinal number idioms - fall at the first hurdle
ordinal number idioms - first and foremost
ordinal number idioms - first base
ordinal number idioms - first come, first served
ordinal number idioms - first-hand
ordinal number idioms
ordinal number idioms - have second thoughts
ordinal number idioms - have second thoughts
ordinal number idioms - have second thoughts
ordinal number idioms - have second thoughts
ordinal number idioms - second chance
ordinal number idioms - second-guess
ordinal number idioms - second hand
ordinal number idioms - second nature
ordinal number idioms - second wind
ordinal number idioms
ordinal number idioms - third degree
ordinal number idioms - third time lucky
ordinal number idioms - third wheel