Seventieth is the ordinal number that comes after sixty-ninth and before seventy-first. It describes the position of something in a sequence when counting by ones: first, second, third... all the way to seventieth.

You might celebrate someone's seventieth birthday when they turn 70 years old. If you're reading a long book, the seventieth page comes after page 69. In a race with many competitors, finishing in seventieth place means 69 people finished before you.

The word can also describe one part when something is divided into 70 equal pieces. If you split a pizza into 70 slices (which would be ridiculous but mathematically possible), each slice would be one seventieth of the pizza. When written as a fraction, one seventieth looks like 1/70.

People also use seventieth when marking significant anniversaries. A company might celebrate its seventieth year in business, or a couple might mark their seventieth wedding anniversary (a rare achievement!). The number 70 itself can represent a milestone worth celebrating, which is why we use the ordinal form seventieth to mark that special position or achievement.