I guess it depends on context, because there seem to be several definitions:
"# a post-town, in the parish of COOLBANAGHER, barony of PORTNEHINCH, QUEEN'S county, and province of LEINSTER, 5 miles (E.) from Maryborough, and 34 3/4 (WSW) from Dublin, near the high road to Maryborough; containing 14 houses and 102 inhabitants. Here are the RC chapel (a neat building), a public school, and a constabulary police station. Adjoining the town is Emo park, formerly Dawson's Court, the splendid mansion of the Earl of Portarlington.-- See COOLBANAGHER.
# Emergency Management Office (USA).
# Emo (an abbreviation of "emotionally-driven Hardcore punk") is a term now broadly used to describe almost any form of guitar-driven alternative rock that expresses emotions beyond traditional punk's limited emotional palette of alienation and rage. It is also used to describe fans of this genre, most commonly teenagers. (e.g., emo kid). The actual term "emo" originated in the mid-1980s D.C. scene, with the band Rites of Spring, as well as bands such as Fugazi, Moss Icon, and Antioch Arrow. ...
# Emo is an Irish filling station chain, owned by DCC. It was created in 2000 when BP Amoco purchased the Burmah filling stations (along with the rest of Castrol). As BP had closed their Irish operations (selling them to Statoil), they had little interest in Burmahs Irish network, and it was purchased by DCC.