The city of Sodom is a city that is mentioned in the Torah, Bible, and Qur'an and according to the Christian Bible was destroyed by God in an act of divine judgement. Basically, Sodom was a city that was filled with sinners - the nature of this sin is still debated by theologians because the Bible is somewhat vague. One belief is that one of the primary sin of Sodom was sexual deviation that extends to include bestiality, homosexuality, pedophilia, rape, perverse/illicit sex, sex with angels. Along with this sort of sexual deviance the people of Sodom were said to be lazy, overfed, reluctant to help the needy, selfish, inhospitable, murderers etc. God basically got fed up with these people and said he was going to destroy the city, however Lot asked him to hold off on his judgement and God agreed to spare the city if Lot was able to find 10 righteous people in the city. Long story short, Lot was unsuccessful, so God ordered him and his family to leave the city and not look back while they left. Lot's wife didn't listen to God and she looked back at Sodom as it was being destroyed by brimstone and fire and was subsequently turned into a pillar of salt.
The word sodomy means "sexual misconduct" is derived from the city of Sodom because of its sexually deviant population.