"square peg in a round hole" happens to be the perfect translation of "square peg in a round hole". What other idioms are there?

The phenomenon of an idiom translating perfectly, word-for-word, into another language, as with the English "square peg in a round hole" and its German equivalent "ein viereckiger Pfahl in einem runden Loch," is known as a lexical equivalent or a direct calque. This occurs when languages share a common conceptual metaphor rooted in a universal human experience or when an expression has been borrowed directly from one language into another, often through historical or cultural proximity. Such idioms are fascinating because they bypass the usual translation challenge where the figurative meaning is preserved but the literal components differ drastically, as in the English "it's raining cats and dogs" versus the French "il pleut des cordes" (it's raining ropes). The existence of these direct equivalents often points to shared folk wisdom, common technological histories, or extensive linguistic exchange.

Numerous other examples exist across language pairs, particularly within European languages due to shared Latin, Greek, and Biblical heritage. The English "to have other fish to fry" finds a precise counterpart in the French "avoir d'autres chats à fouetter" (to have other cats to whip) and the Spanish "tener otras cosas que hacer" (to have other things to do), demonstrating slight variations on a common theme of having more important matters. More exact parallels include the English "walls have ears," which is "les murs ont des oreilles" in French and "las paredes oyen" in Spanish. Similarly, "to kill two birds with one stone" is "uccidere due piccioni con una fava" in Italian (using a single fava bean) and "matar dos pájaros de un tiro" in Spanish (with a single shot). These reflect not just shared meaning but a nearly identical construction of the metaphor, suggesting a common proverbial lineage.

The mechanism behind these parallels is typically historical diffusion rather than independent invention. The widespread European idiom for something being extremely rare or non-existent, "when pigs fly," appears in German as "wenn Schweine fliegen könnten" and in Swedish as "när grisar flyger," indicating a likely common origin. Biblical proverbs are another rich source; "an eye for an eye" is directly translatable into many languages from the original texts. However, even seemingly perfect translations can carry subtle differences in connotation, frequency of use, or contextual appropriateness. For instance, the Danish "at slå to fluer med et smæk" (to kill two flies with one slap) is a direct conceptual match for "killing two birds with one stone," yet the choice of smaller prey and a domestic action slightly alters the idiom's perceived scale and tone.

The implications of studying these equivalents extend beyond mere linguistic curiosity. For translators and cross-cultural communicators, they represent rare, low-friction points where meaning transfers without distortion, reducing the risk of misinterpretation. For linguists, they serve as markers of cultural contact and the migration of ideas. However, reliance on them can be a pitfall if assumed to be more common than they are; for every perfect match like "the straw that broke the camel's back" ("la goutte d'eau qui fait déborder le vase" in French, or the drop of water that makes the vase overflow), there are countless idioms that are utterly opaque in direct translation. This makes their existence not a rule but a useful exception that highlights the intricate and often divergent paths of metaphorical thought across cultures.