Term coined by Carles of Hipster Runoff referring to a style of music that emerged in Summer 2K9 primarily from the Brooklyn music scene.
Chillwave generally features a fuzzy sound with a slow but steady pulse-beat that hearkens back to 1980's pop culture; it may sound like the radio being played in the car during an episode of Miami Vice recorded on a crappy VHS tape and played back after said tape's been melting in the attic for a few years.
Although it can be either electronic or markedly lo-fi, lyrical and sonic themes hinge nostalgically on a longing for lazier times and may or may not involve references to inert romance or drug use.
I went on Hype Machine and Gorilla vs. Bear and downloaded every bloggable track by Neon Indian, Washed Out, and Memory Cassette -- I love chillwave.
When you and one or more friends are sitting together and one of them gets the chills and then all of you get the chills as a result. sort of like a dominoe effect. Like yawning.
Shane: *Gets the chills*
Justin: *gets the chills too* woah....that was a chill wave!