Signalling Vs Signaling Which Spelling Is Right

The Spelling Debate That Won't Die

You've probably seen both versions floating around. Signalling with two Ls. Signaling with one. You open a document and suddenly you're questioning everything. I've been editing technical documentation long enough to know which one to use, and it's not as complicated as people make it. Both are correct. That's the short answer. The double L belongs to British English and its descendants—Canadian, Australian, New Zealand. The single L is American English. Merriam-Webster lists signaling. Oxford lists signalling. Neither is wrong, they just come from different style guides. The root is the word signal. When you add a suffix that starts with a vowel, English has a doubling rule. If the stress falls on the final syllable of a one-syllable word or a word ending in stress-final consonant-vowel-consonant, you double that final consonant before adding -ing, -ed, -er. Signal fits that pattern. The stress is on the second syllable: sig-NAL. So logically, signalling makes sense. But American English simplified this during Noah Webster's spelling reforms in the early 1800s. He wanted American spelling to be more phonetic and less tied to etymology. Signaling survived his edits.

I ran into this problem a few years ago when a client in London sent me a style guide that mandated double L. I'd been writing everything with a single L based on my default US settings. The confusion showed up in a telecoms project where the UK team used signalling throughout their RFCs and the US team used signaling in their internal docs. Merging the two repositories was a nightmare of find-and-replace operations. I ended up writing a small script that checked the target style guide and normalized everything automatically. Saved me about three hours of manual editing. The practical reality is that most professional environments pick one and stick with it. If you're writing for a US audience, use signaling. If you're writing for international or Commonwealth readers, use signalling. If you're writing for yourself and nobody else will read it, pick one and be consistent. The internet doesn't care, but your editor might. There's a common misconception that one form is more formal or more correct than the other. It's not. Both appear in peer-reviewed journals, both are used by government bodies, and both get flagged by grammar checkers depending on which variant you have selected. Grammarly, for instance, will mark one as incorrect if your locale is set to the opposite variant. This trips up a lot of people. You paste a sentence into a checker and suddenly you're second-guessing a spelling that's been in dictionaries for centuries.

If you need a definitive reference, the Chicago Manual of Style uses signaling. The Oxford English Dictionary prefers signalling. The Associated Press Stylebook goes with signaling. The BBC's own style guide uses signalling. You'll notice a pattern there. One edge case that catches people out: the noun form. Signal stays signal in both variants. It's only the verb forms that diverge. Signaled versus signalled. Signaler versus signaller. The doubling rule applies consistently across all derived forms in British English. In American English, none of them double. Just keep that straight when you're working across both variants in the same document. For most purposes, the American spelling will save you typing two characters per occurrence. Not a huge deal, but if you're writing a lot of technical content, it adds up. Also, most word processors default to US English unless you change it. I've lost count of how many times I've submitted a document only to see red squiggles under signalling because the editor hadn't switched locales. It's a minor inconvenience that signals nothing about the actual correctness of the word.