The Opposite of December... A Season of Separation is the debut full-length album by American metalcore band Poison the Well. It was released on December 14, 1999. Influential in the early popularization of metalcore around the turn of the 21st century, the album was the band's first on Trustkill Records and is now recognized as a landmark album in the genre due to its quality and influence. The album was the band's first release to appear on CMJ's charts, reaching number 9 on the Loud Rock chart in May 2000. It had sold 30,000 copies by 2002. The release received numerous reissues on various formats over the years through such record labels as Good Life Recordings, Roadrunner Records, Shock Records and Rise Records and was digitally remastered in 2012.

Metalcore is a fusion genre combining elements of extreme metal and hardcore punk, that originated in the late 1980s. Metalcore is noted for its use of breakdowns, which are slow, intense passages conducive to moshing, while other defining instrumentation includes heavy guitar riffs often utilizing percussive pedal tones and double bass drumming. Vocalists in the genre typically perform screaming, more popular bands often combine this with the use of standard singing, usually during the bridge or chorus of a song. However, the death growl is also a popular technique within the genre.