Relatives Revisited: Essential Tips for Defining and Non-Defining Clauses

 

In the vast and winding lanes of English grammar, relative clauses are the grammatical cousins who show up to every gathering — sometimes expected, often a little confusing, and always with a story to tell. They’re the clauses that help you explain which sandwich, what house, or who exactly you’re talking about. And like many relatives, they come in two types: defining and non-defining. Understanding which one to use is less about family politics and more about clarity, style, and—let’s be honest—avoiding catastrophic misunderstandings.

Let us begin with defining relative clauses. These are the workhorses of precision. They tell you exactly who or what you mean. In a sentence like “The student who forgot her laptop is waiting outside,” the clause “who forgot her laptop” is not just extra information—it’s essential. If you removed it, you’d be left with “The student is waiting outside,” which is far too vague in a room full of students. The defining relative clause points out which student you mean.

English, being the polite and yet ever-so-practical language it is, usually introduces these clauses with relative pronouns: who, which, that, whose, and where. While prescriptivists may raise an eyebrow at “that” being used for people (“the girl that won the prize”), this is common in informal usage, particularly in British English, where a preference for brevity sometimes trumps grammatical primness.

A crucial feature of defining clauses is that they are not separated by commas. They are married to the noun they describe—no distance, no space for ambiguity. For students who speak Romance languages, this may come as a cultural shock. In Spanish or French, clauses tend to trail behind with a certain decorative flair, but in English, we like our meanings sharp, clipped, and efficiently packed into the front end of a sentence. Perhaps it’s the influence of centuries of merchant correspondence and public notices: “Do not feed the dog that bites,” not “Do not feed the dog, which bites,” unless you want lawsuits.

Now, non-defining relative clauses—these are the flamboyant aunts of the grammar family. Full of detail, charm, and entirely unnecessary information (grammatically speaking), they’re often set off by commas and introduced with a leisurely pause. For example: “My neighbour, who loves jazz, waters her plants at midnight.” You could remove “who loves jazz”, and you’d still know who you’re talking about: “My neighbour waters her plants at midnight.” The extra clause adds colour, a touch of eccentricity, but it doesn’t change the subject of the sentence.

These clauses tend to have stricter etiquette. Unlike defining clauses, they never use “that”. It’s “which” or “who”, thank you very much. So it’s “The building, which was built in 1890, is now a hotel”, not “The building that was built in 1890…” (unless you're redefining which building, in which case you may have wandered back into defining territory). These commas, then, are not optional frills; they’re essential road signs that tell the reader: pause, take a breath, this is a scenic detour.

The distinction between these two clause types isn’t just academic—it’s sometimes a matter of life, death, or at least social catastrophe. Consider this:

1. “The guests who arrived late were not served dinner.”
2. “The guests, who arrived late, were not served dinner.”

The first implies that only the latecomers were denied their meal—possibly just desserts. The second implies that all the guests arrived late, and none were served dinner, possibly due to a terrible scheduling mix-up or an overzealous maître d’. The difference? Those humble commas.

For English learners, this punctuation minefield can be disheartening. Add to that the slippery nature of spoken English—where commas vanish into thin air, and pauses vary wildly depending on whether the speaker’s from Manchester or Mumbai—and things can get murky. But fear not. There are a few dependable signals. If the clause is necessary to identify the noun, it’s defining—no commas. If it’s just additional information, it’s non-defining—commas required.

Let’s turn briefly to the curious case of “whose”. It’s the relative clause equivalent of that one grammar rule no one wants to enforce but everyone grudgingly follows. “Whose” is the only relative pronoun we use for possession, and it works for people and things alike—though using it for objects sometimes raises eyebrows among style purists. For instance: “The company whose offices are in London…” is perfectly standard, even if a little anthropomorphic. After all, we speak of “a country whose traditions date back centuries” without wondering if the country owns a wardrobe.

Advanced learners might also find themselves entangled in restrictive vs non-restrictive choices when writing more formal texts. Academic English tends to lean heavily on non-defining clauses to add context, cite authors, and insert polite parenthetical nods: “Smith (2020), who argues against this position, suggests…” The style is elaborate, yes, but deeply baked into scholarly prose.

At the more casual end of the spectrum, modern spoken English is doing all sorts of acrobatics with relative clauses. Relative pronouns are often dropped altogether: “The girl I told you about” instead of “The girl who I told you about.” While perfectly acceptable in speech, these shortcuts rarely belong in formal writing—though they do signal where the language is quietly evolving.

Teaching relative clauses effectively, then, involves more than just chalking up grammar tables on the whiteboard. It’s about drawing attention to nuance. It’s about showing students that punctuation isn’t just decorative—it’s structural. It’s the scaffolding that holds up meaning. A good exercise is to present students with examples and ask: “Could you remove the clause and still know who or what this is about?” If yes, commas. If no, leave them out.

Perhaps most importantly, we need to reassure learners that getting it slightly wrong won’t derail communication entirely. Native speakers bungle their relative clauses all the time (often with gusto), and few conversational breakdowns are caused by a misplaced comma. But in writing—particularly academic or professional writing—getting this right not only avoids ambiguity but also signals linguistic confidence.

So, the next time you find yourself wondering whether to include those commas, ask yourself: is this relative clause essential or merely descriptive? Is it pinning down your meaning, or dressing it up in metaphorical sequins? The answer will guide your punctuation—and, like any well-behaved relative, keep your sentences in line.

 

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