Initialism of pumpkin spice latte(“coffee drink made with a mix of fall spice flavors”).
2016 September 1, Megan McCluskey, “Starbucks Pumpkin Spice Lattes Are Finally Here”, in Time[1]:
Starbucks has sold 200 million PSLs since the cinnamon-y sweet coffee was first introduced in 2003, making it the most popular seasonal beverage ever, according to a Starbucks spokesperson.
2018, “Coffee Is a Flavor”, in Coffee[…][2], Time Home Entertainment, →ISBN:
Chef and TV personality Anthony Bourdain once said, “I would like to see the pumpkin-spice craze drown in its own blood.” Railing against the mighty PSL is like going on Instagram to complain about photos of Mason jars.