There is an urban legend that the British slang term “bloody” is derived from the phrase “by our Lady” which is blasphemous and therefore ought not to be said, or perhaps the oath “‘s Blood,” as being short for “God’s Blood”. However, Steven Pinker, in his book The Stuff of Thought, and others have made the point that, while blasphemy is certainly one potent source of cuss words, the real goal of a good swear is to transgress the boundaries of taboo–and one of those boundaries is at the edge of our skin.
“Bloody” is a strong word all by itself, referencing things that should go unseen, and the spilling of which suggest violence, danger, possibly disease. It holds the power to shock because it immediately heightens the tension about these possibilities–the piercing of the human body, the precious stuff within spilling, staining, and sickening those around. Other insults, such as Shakespeare’s “a plague on both your houses,” underscore a similar concern with that critical boundary of health, wholeness whose crossing may result in death.
However, the OED offers a different explanation for the word, and points to the transgression of a different boundary, in suggestion that the origin of its current use goes back to the 1750’s and the term “blood” as a short-hand for “blue-blood” meaning a member of the nobility. So, “bloody” would refer to doing something in the manner of an aristocrat–but its application as a derogatory word, as it is so clearly intended by those who employ it and treated by those who disdain it, represents the lower classes displaying a strong and negative opinion toward their theoretical betters.
The OED describes this word as “now constantly in the mouths of the lowest classes, but by respectable people considered ‘a horrid word’, on a par with obscene or profane language. . .” The entire purpose of words like this is to offend so-called “respectable people,” perhaps in this case, originally by claiming that the low-born had something in common with the high.
When I’m creating fantasy realms, the consideration of language, especially that employed by my characters, is significant. What words do they choose and why? Which characters would use a certain word or kind of word, and which would not? In a fantasy novel centered on medieval surgery, “bloody” as an adjective is highly functional. “Bloody” as a modifier suggesting the significance of the statement is handy as well, and “bloody” as a word that implicates the boundary between the healthy self and the chance of disease or injury, as well as one that points to class conflict between lowborn individuals like my protagonist, Elisha, and the nobles he finds himself confronting is excellent. To be able to suggest all of these meanings in a single adjective? Bloody astounding!