Many theories have been put forward for the origin of
bloody as a
profanity. One theory is that it derives from the phrase
by Our Lady, a
sacrilegious invocation of the
Virgin Mary. The abbreviated form
By'r Lady is common in
Shakespeare's plays around the turn of the 17th century, and interestingly
Jonathan Swift about 100 years
later writes both "it grows by'r Lady cold" and "it was bloody hot walking to-day"[SUP]
[1][/SUP] suggesting that a transition from one to the other could have been under way. In the middle of the 19th century Anne Brontƫ writes in
The Tenant of Wildfell Hall: "I went to see him once or twice ā nay, twice or thrice ā or, by'r lady, some four times" (Chapter XXII).
Others regard this explanation as dubious.
Eric Partridge, in
Words, Words, Words (
Methuen, 1933), describes this as "phonetically implausible".
Geoffrey Hughes in
Swearing: A social history of foul language, oaths and profanity in English (
Blackwell, 1991), points out that "by my lady" is not an adjective whereas
bloody is, and suggests that the slang use of the term started with
bloody drunk meaning "fired up and ready for a fight".
Another theory is that the offensive use of the word arose during the
Wars of the Roses when Royalty and nobility or those "of the blood" (meaning
blue-blooded descendants of Charlemagne) wrought death and the most bloody destruction on England. Elizabeth I is also supposed to have used it when referring to her elder sister,
Mary, due to her persecution of Protestants.
Another thought is that it simply comes from a reference to blood, a view that
Eric Partridge prefers. However, this overlooks the considerable strength of social and religious pressure in past centuries to avoid profanity. This resulted in the appearance or
minced-oath appropriation of words that in some cases appear to bear little relation to their source:
Crikey for "
Christ";
Gee for "
Jesus";
Heck for "
Hell";
Gosh for "
God";
dash,
dang or
darn for "
damn". These, too, might be considered implausible etymologies if looked at only from the point of view of phonetics. Given the context in which it is used, as well as the evidence of Swift's writing, the possibility that
bloody is also a
minced oath (or more precisely, a slang usage of an otherwise legitimate word masquerading as a minced oath) cannot be lightly dismissed.[SUP]
[citation needed][/SUP]
It has also been surmised that
bloody is related to the Dutch
bloote, "in the adverbial sense of entire, complete, pure, naked, that we have transformed into
bloody, in the consequently absurd phrases of
bloody good,
bloody bad,
bloody thief,
bloody angry, &c, where it simply implies completely, entirely, purely, very, truly, and has no relation to either blood or murder, except by corruption of the word."[SUP]
[2][/SUP]
Another possibility is that the word may just be a contraction of "By the Lord's Day". And again, it could simply be borrowed (only slightly changed) from German "blode" meaning "silly, stupid" , pronounced "blerder". The phonetic conversion to "bloody" then makes more sense than in other explanations, because the origin then means that bringing "blood" into the language is a pure happenstance. Many have been puzzled as to why "blood" should be used in the sense implied in expressions such as "bloody screwdriver", "bloody car", or "bloody good".
Alls well in the neighborhood. 
