Well, the Merriam-Webster definition is “running or turning back in a direction opposite to a former course,” but in this instance we’re wondering more in terms of what it means when your song goes “recurrent” at radio.

Let’s start from the beginning, with a record being serviced to radio. If a station likes it, they then add it to one of their “current” rotation categories, and if enough stations add that particular song, the combined airplay will cause it to debut and then work its way up the airplay charts, such as those found on Mediabase.

The songs that make up a station’s “current” rotation will fit into various labeled categories: “light”, “medium”, “heavy” or “power”, all of which signify the relative amount of exposure a song will get on the station. But all of those songs, in all of those categories, are considered “current”.

Over the following weeks, as more and more stations “add” the record (or increase their rotations), the song flies up the charts, amassing higher and higher spin-counts and attaining higher and higher chart positions (which is actually defined as lower and lower: Top-10, Top-5, etc) on the way to #1. But at a certain point however, a song will reach its peak and start to decline back down the chart.

Generally speaking, a song will rise up a chart much faster than it falls back down, especially if it’s a massive hit, and it’s this situation that can create a real bottleneck, as airplay charts (unlike sales charts) are designed to reflect what’s on the way up. To help alleviate these traffic jams and create space for the new songs that are coming up, the “recurrent” rule gets applied.

For Mediabase, the rule is actually very simple — “Songs trending down in spins below No. 10 are removed after 20 weeks.”

What that means, is that as long as the song is on the way up the chart (or gaining in spins), you’re safe. If the song has been on the chart for less than 20 weeks, safe again. However, if you’re out of the Top-10, have been losing spins for consecutive weeks and are now entering your 20th week on the chart, you’ll soon be shifted to “recurrent” status and removed from the chart.

But what causes this loss of spins that eventually culminates with being labeled “recurrent”?

Depending on the station, the top “current” rotations can range anywhere from 10 to 85 spins per week. With high-rotation songs, there exists the risk of a condition known as “burn”, which is when listener fatigue starts to develop — it’s not that listeners don’t like the song anymore, it’s just that they’re reached the point where they want to hear something else. Stations will evaluate songs once they hit a specific threshold level (which can range from 200 cumulative spins to over 1500, depending on the station). If the song is starting to show signs of “burn,” its rotation will be downgraded, resulting in reduced exposure. If enough stations downgrade in the same period of time, this can create an overall downward trend in spins, opening up the possibility for the “recurrent” rule being applied to it on the chart.

For all charting songs, the eventual transition to “recurrent” is just part of the life cycle. Even though a song may “disappear” off the charts, it’s not gone from the airwaves, as nearly every station has a dedicated “recurrent” category rotation where these songs can remain for an extended period of time (in many instances, for years.) These “recurrent” rotation categories could be viewed almost like a “retirement home” for hit songs, a place where they’re still active, but their on-air exposure has slowed down.