Being a linguist — and someone who has tried to learn several languages (including English) in addition to my mother tongue (Flemish Dutch) — I have an annoying habit: instead of paying attention to what people are saying, I often get distracted by how they are saying it. The other day, this happened again in a meeting with colleagues.I started writing down some of the expressions my colleagues were using to communicate their ideas that may be puzzling for users of English as a second or additional language. In a span of about five minutes, I heard “it’s a no-brainer,” “to second something,” “being on the same page,” “to bring people up to speed,” “how you see fit,” “to table something” and “to have it out with someone.” These are all expressions whose meanings do not follow straightforwardly from their lexical makeup — they’re called idioms by lexicologists. Idioms are part of daily communication. But this anecdote also suggests that we take it for granted that such expressions are readily understood by members of the same community. However, when it comes to people who are new to said community, nothing could be further from the truth.Idioms and the limits of language proficiencyResearch conducted at the University of Birmingham several years ago revealed that international students for whom English is an additional language often misunderstand lecture content because they misinterpret their lecturers’ metaphorical phrases, including figurative idioms. More recent research confirms that English idioms can remain elusive to second-language learners even if the expressions are intentionally embedded in transparent contexts.One of my own recent studies, conducted with international students at Western University in Canada, also found that students incorrectly interpreted idioms and struggled to recall the actual meanings later on after being corrected.This shows just how persistently confusing these expressions can be.It’s worth mentioning that we’re talking about students who obtained high enough scores on standardized English proficiency tests to be admitted to English-medium universities. Knowledge of idioms appears to lag behind other facets of language.When literal meanings get in the wayThe challenge posed by idioms is not unique to English. All languages have large stocks of idioms, many of which second-language learners will find puzzling if the expressions do not have obvious counterparts in their mother tongue. There are various obstacles to comprehending idioms, and recognizing these obstacles can help us empathize with those who are new to a community. For one thing, an idiom will inevitably be hard to understand if it includes a word that the learner does not know at all.However, even if all the constituent words of an expression look familiar, the first meaning that comes to a learner’s mind can be misleading. For example, as a younger learner of English, I was convinced that the expression “to jump the gun” referred to an act of bravery because, to me, the phrase evoked an image of someone being held at gunpoint and who makes a sudden move to disarm an adversary.I only realized that this idiom means “to act too soon” when I was told that the gun in this phrase does not allude to a firearm but to the pistol used to signal the start of a race. I also used to think that to “follow suit” meant taking orders from someone in a position of authority because I thought “suit” alluded to business attire. Its actual meaning — “to do the same thing as someone else” — became clear only when I learned the other meaning of suit in card games such as bridge.The idea that idioms prompt a literal interpretation may seem counter-intuitive to readers who have not learned a second language because we normally bypass such literal interpretations when we hear idioms in our first language. However, research suggests that second-language learners do tend to use literal meanings as they try to make sense of idioms. Unfortunately, when language learners use a literal reading of an idiom to guess its figurative meaning, they are very often misled by ambiguous words. For example, they will almost inevitably misunderstand “limb” in the idiom “to go out on a limb” — meaning “to take a serious risk” — as a body part rather than a branch of a tree.Recognizing the origin of an idiomatic expression can also be difficult because the domains of life from which certain idioms stem are not necessarily shared across cultures. For example, learners may struggle to understand English idioms derived from horse racing (“to win hands down”), golf (“par for the course”), rowing (“pull your weight”) and baseball (“cover your bases”), if these sports are uncommon in the communities in which they grew up. A language’s stock of idioms provides a window into a community’s culture and history.Same language, same idioms? Not exactlyIdiom repertoires vary across communities — whether defined regionally, demographically or otherwise — even when those communities share the same general language. For example, if an Aussie were to criticize an anglophone Canadian for making a fuss by saying “you’re carrying on like a pork chop,” they may be lost in translation, even if there isn’t much of one. At least, linguistically that is. Although people may have learned a handful of idioms in an English-language course taken in their home country, those particular idioms may not be the ones they will encounter later as international students or immigrants. The moral is simple: be aware that expressions you consider perfectly transparent because you grew up with them may be puzzling to others. We need to have more empathy for people who are not yet familiar with the many hundreds of potentially confusing phrases that we use so spontaneously.Frank Boers receives funding from the Social Science and Humanities Research Council of Canada.