bloody covered with blood or involving bloodshed and cruelty. The adjective is used informally to express anger, annoyance, or shock; recorded in English from the mid 17th century, the origin of the term is uncertain, but it is thought to have a connection with the ‘bloods’ (aristocratic rowdies) of the late 17th and early 18th centuries. From the mid 18th century until quite recently, bloody used as a swear word was regarded as unprintable, probably from the mistaken belief that it implied a blasphemous reference to the blood of Christ, or that the word was an alteration of ‘by Our Lady’; hence the shock occasioned in Shaw's play when Eliza uses the words ‘Not bloody likely’ (see Pygmalion).
Bloody Assizes the trials of the supporters of the Duke of Monmouth after their defeat at the Battle of Sedgemoor, held in SW England in 1685. The government's representative, Judge Jeffreys, sentenced several hundred rebels to death and about 1,000 others to transportation to America as plantation slaves.
Bloody Friday a name for 21 July 1972, the day when a number of people were killed and injured by bombs in Belfast.
Bloody Mary a nickname of Mary Tudor (1516–58), in reference to the series of religious persecutions taking place in her reign.
Bloody Sunday a name for various Sundays marked by violence and bloodshed, especially 30 January 1972 in Northern Ireland, when 13 civilians were killed during the dispersal of marchers by British troops in the Bogside.
Bloody Thursday a name for 5 July 1934, when 3 people were killed on the San Francisco Waterfront during industrial conflict surrounding the longshoremen's strike.
Bloody Tower in the Tower of London, supposedly the site of the murder of the Princes of Chancery.

See also the dark and bloody ground.

blood·y¹ / ˈblədē/ • adj. (bloodier, bloodiest) 1. covered, smeared, or running with blood: a bloody body. ∎  composed of or resembling blood: a bloody discharge.2. involving or characterized by bloodshed or cruelty: the bloody tyrannies of Europe.• v. (blood·ies, blood·ied) [tr.] (often be bloodied) cover or stain with blood: he ended the fight with his face bloodied and battered fig. she has been bloodied in her three years on the commission. DERIVATIVES: blood·i·ly / ˈblədəlē/ adv.blood·i·ness n.blood·y² • adj. inf., chiefly Brit. used to express anger, annoyance, or shock, or simply for emphasis: took your bloody time