What's the etymology of an engineering/software bug?

Question

I read the Wikipedia page on Software bugs. It does have a section on its etymology. Albeit interesting it doesn't answer my question but merely notes that the term bug was used in 1878:

Use of the term "bug" to describe inexplicable defects has been a part of engineering jargon for many decades and predates computers and computer software; it may have originally been used in hardware engineering to describe mechanical malfunctions. For instance, Thomas Edison wrote the following words in a letter to an associate in 1878:

It has been just so in all of my inventions. The first step is an intuition, and comes with a burst, then difficulties arise — this thing gives out and [it is] then that "Bugs" — as such little faults and difficulties are called — show themselves and months of intense watching, study and labor are requisite before commercial success or failure is certainly reached.

Baffle Ball, the first mechanical pinball game, was advertised as being "free of bugs" in 1931. Problems with military gear during World War II were referred to as bugs (or glitches).

A page from the Harvard Mark II electromechanical computer's log, featuring a dead moth that was removed from the device The term "bug" was used in an account by computer pioneer Grace Hopper, who publicized the cause of a malfunction in an early electromechanical computer. A typical version of the story is given by this quote:

In 1946, when Hopper was released from active duty, she joined the Harvard Faculty at the Computation Laboratory where she continued her work on the Mark II and Mark III. Operators traced an error in the Mark II to a moth trapped in a relay, coining the term bug. This bug was carefully removed and taped to the log book. Stemming from the first bug, today we call errors or glitches in a program a bug.

So why was a bug called bug in the first place (e.g. before 1878)? Also, was nobody in Hopper's lab aware of the engineering meaning of bug?

Answer 1

This first sourcing I take directly from my paper copy of the The Oxford Dictionary of English Etymology (c. 1966, 1996 reprint)

Here we have two etymologies for the word bug.

The less appropriate etymology is as "insect, beetle (as still in U.S.)" with reference to a 16th century occurrence "in turd-bug dung beetle". It is next noted "Origin unascertained" with indication that this is possibly an alteration of the Old English word buddle.

The more appropriate sense, and I think clearly the context from whence this entered into the use we are looking for (I expand the abbreviations to form at least a few complete sentences, but in general I quote with liberties):

bug object of dread. First seen in the English language with this meaning in the 14th century. The earliest of several words, mostly evidenced from the 16th century, of similar form and meaning ('goblin', 'spectre', 'bugbear', 'bogey'), the connexions of which are obscure; namely the obsolete dialectic words 'bog', 'boggard', 'bogle' (Dunbar), 'bogle-bo', BUGABOO, BUGBEAR, and the more recent BOGEY. Comparison with Welsh 'bwg', 'bwgan' meaning ghost, hobgoblin,....

This etymology continues, but that is the heart of the context we are looking for, and I suspect the earlier portion of the best known total path to the more recent 19th and 20th century etymological traces described in the cited Wikipedia article.

I have two other good paper sourcings that cast even more references and details along this line:

In The Merriam-Webster New Book of Word Histories (c. 1991) The authors point out that "A Middle English bugge was either a scarecrow or a hobgoblin." The author sources that 14th century OED reference as being from the 1382 Wycliffe bible.

In the Dictionary of Word Origins by John Ayto (c. 1990), the author states, "Originally the word bug meant 'something frightening'". He goes on to say. "It is one of a set of words (others are 'bogle' and perhaps 'bugaboo') for alarming or annoying phenomena, usually supernatural, whose interrelationship and ultimate source have never been explained."

That last sourcing sounds distinctly like a software bug to my ears in the sense of some alarming and annoying thing that might (initially) seem supernatural.

Answer 2

From Oxford Dictionaries:

The term in fact originates not with computer pioneers, but with engineers of a much earlier generation. The first example cited in the 20-volume historical Oxford English Dictionary is from the Pall Mall Gazette of 11 March 1889:

Mr. Edison, I was informed, had been up the two previous nights discovering 'a bug' in his phonograph - an expression for solving a difficulty, and implying that some imaginary insect has secreted itself inside and is causing all the trouble.

In the computing context:

In September 1947, operators of the Mark II Aiken Relay Computer found something curious trapped between points at Relay #70, Panel F: A moth. The term became popular after Grace Hopper logged the “first actual case of bug being found” in her diary, and stuck the culprit to the page.