Quaternary is an adjective that means fourth in order or rank. 

The Latin word ‘quattuor’ (KWAT too or) denotes the number ‘four.’ Just as we use the words ‘primary,’ ‘secondary’ and ‘tertiary’ to describe things that are first, second and third in rank or order, our word of the day refers to something fourth in order. Here’s an example:

I wasn’t the fastest runner on our high school track team, but I take some pride in being the quaternary-ranked runner in the one-hundred-meter dash. Unfortunately, there’s no medal handed out for fourth place.