Plural of “cul-de-sac”

The plural of cul-de-sac is culs-de-sac (some dictionaries also accept cul-de-sacs).

Why

"Cul-de-sac" is a French phrase literally meaning "bottom of the bag," borrowed directly into English to describe a dead-end street with a rounded turnaround. In French grammar, the phrase pluralizes the head noun "cul" (bottom), giving "culs-de-sac," though English has increasingly regularized the plural to the very end, "cul-de-sacs," as the phrase has become fully naturalized in everyday American real-estate and neighborhood vocabulary.

Unlike "attorney general" or "court martial," which remain tied closely to formal legal registers where their French structure stays more consciously recognized, "cul-de-sac" entered everyday residential and urban-planning vocabulary so thoroughly that most English speakers today treat it as a single ordinary compound noun rather than as a French phrase with an internal grammatical structure, which likely explains why "cul-de-sacs" has become the dominant, widely accepted plural in modern usage. "Culs-de-sac" survives mainly in more formal, deliberately careful, or British usage, where writers are more likely to be conscious of the phrase's French origin and grammar.

Usage note

"Cul-de-sacs" is now the standard, most common plural in everyday American English, including real-estate listings and casual conversation ("the neighborhood has several cul-de-sacs"). "Culs-de-sac" remains correct and appears more often in British usage or in writing that wants to signal careful attention to the phrase's French origin, but it will read as unusual or overly formal to many American readers.

Urban planners distinguish "cul-de-sacs" as a specific street design with real traffic and safety implications, generally reducing through-traffic and increasing pedestrian safety within a residential loop, but also complicating emergency vehicle access and walkability between neighborhoods, a design tradeoff much discussed in modern urban planning literature. The phrase's literal French meaning, "bottom of the bag," evokes the shape of a dead-end passage that narrows to a closed point, the same image that gave the term to anatomical and medical usage describing a pouch-like closed cavity in the body, an entirely separate technical sense from the everyday street meaning.

Common real mistakes

The main point of variation, rather than outright error, is choosing between "cul-de-sacs" and "culs-de-sac"; American writers should default confidently to "cul-de-sacs" for general audiences, while "culs-de-sac" is a defensible, more formal alternative rather than a mistake. Writers should also avoid the redundant "cul-de-sac street," since the phrase already specifies a type of street on its own.

The wider pattern

"Cul-de-sac" belongs to a small group of French phrases borrowed wholesale into English that show genuine variation between preserving the original French internal plural and regularizing to a plain English -s at the end, a tension also visible, in a different form, in words like "court-martial" and "attorney-general," though "cul-de-sac" has drifted further toward full English regularization than either of those more formally preserved legal titles.

Examples

• The new subdivision was designed with several quiet cul-de-sacs.
• Children often play safely in cul-de-sacs away from through traffic.
• The realtor highlighted the cul-de-sacs as a selling point for families.
• Emergency planners noted that cul-de-sacs can complicate evacuation routes.
• Several cul-de-sacs in the neighborhood share a single connecting road.
• The city council debated whether to approve more cul-de-sacs in new developments.
• Homes on cul-de-sacs often command higher resale prices.
• The map marked all the dead-end cul-de-sacs in red.
• Some urban planners now favor connected streets over isolated cul-de-sacs.
• The survey asked residents whether they preferred living on cul-de-sacs or through streets.
• Kids gathered in the cul-de-sacs for evening bike rides.
• The developer clustered the cul-de-sacs around a shared park.
• The two cul-de-sacs were connected by a narrow walking path.
• Trick-or-treaters flocked to the well-decorated cul-de-sacs each Halloween.
• The new phase of the subdivision added four more cul-de-sacs.
• Surveyors measured each of the cul-de-sacs for the site plan.