Definition of screamo:
(n) :
(music) A genre of aggressive lo-fi guitar-driven music with predominantly screaming vocals, while preserving structural aspects of the emocore/hardcore emo genres of the early 1990's.
(n) :
(music) A genre of guitar-driven music combining late 1990's emo indie rock with interludes of screaming vocals, often accompanied by hardcore or metalcore guitar riffs.
(n) :
(music) Any punk rock-inspired music that involves screaming vocals, typically referring to the genres described above as well as certain subgenres of hardcore punk.
(n) :
(music, often derogatory) Any aggressive music with screamed vocals.