What Does "by the by" Mean?

“By the by,” sometimes also written “by the bye,” is an English idiomatic expression that means “incidentally” or “beside the point.” It is usually most common in British English; Americans more often say “by the way” in the same circumstances. Like most idioms, the meaning isn’t fixed and usage isn’t always standard. Still, in most cases, this particular string of words is most commonly used to add an aside onto a conversation or to change the topic slightly. Many modern readers and speakers of English consider the construction somewhat antiquated, and it is not as common today as it was in the past. Linguistics scholars usually agree that it was most popular during the eighteenth and early nineteenth centuries. It is still generally understood today, but may be seen as formal or dated.

By definition, an idiom is a phrase or statement that has acquired an understood meaning that is different from its literal interpretation. The origin of the phrase “by the by” is not entirely clear, but it may be related to the word “byway,” which means a secondary road or service road that runs as something of an offshoot to the main thoroughfare. Traveling the byways of a conversation would mean moving to related topics or tangents. The American expression “by the way” likely has similar origins.

The expression is most commonly used to slightly change a topic of conversation to something that may be related but not exactly the same. For example, if two people are discussing parties, one may say, “By the bye, I wanted to let you know that my son’s birthday party will be next Saturday.” It can also be used to add personal insights or commentary into a conversation, or as a means of introducing gossip or speculation.

It can be difficult to define why, exactly, people choose this expression rather than just using a more direct transition or saying something more opaque like “incidentally.” Much of it is probably force of habit or local trend. Idiomatic expressions in general can help to set a familiar or informal tone. Sports writing is one place where idioms such as “taking it to the house” or “threading the needle” are often appropriate and even necessary to convey meaning. Creative writing and poetry are other areas where idioms may be frequently used. “By the by” is usually most common in spoken conversation, typically in casual settings, but there are always exceptions.

Idiomatic expressions can often cause a great deal of confusion because their meanings are usually not obvious from the words themselves. Taken alone, the words “by the by” don’t really mean much of anything, at least not anything that makes any sense. Native speakers usually understand it as a matter of convention and usage, though this typically has to be learned.

The same is true for basically all idioms. For example, to say it’s raining cats and dogs does not mean that animals are falling from the sky; it means that it is raining very hard. Similarly, a candidate who is running for president is not literally running. Idioms are specific to a particular culture as well as language, so idiomatic phrases used in the United States may not be readily understood in other English-speaking countries, and vice versa.

Memorization and frequent practice with local speakers are often the only ways for people to learn and remember idioms like this one. For this reason, the use of idioms in certain situations can cause confusion and may need to be avoided. In international correspondence, for example, they may be misunderstood and in certain circumstances could be offensive. Those writing for academic or business purposes may also find that idioms are too informal or distracting.