Most of the languages of India and Europe devolved from one language that existed about 5000 years ago. It is called Proto-Indo-European or just PIE (and we offer you a slice every day in our Good Word History). We think it was spoken somewhere around today's Poland-Russia border. What happened to it?

As the population grew, it began to spread into India and across Europe. As it did, accents or "dialects" began to arise that distinguished PIE as spoken in different regions. For example, the sound [bh] ([b] with a puff of air) became [f] in Latin but plain [b] in Germanic languages, so bher- "carry" became ferre "carry" in Latin and bear in English, a Germanic language.

Once the differences between Proto-Germanic, Proto-Celtic, Proto-Italic, and other dialects became so great that the people speaking these dialects could no longer understand each other, their dialects were different languages. These languages then began breaking up in to dialects and the process repeated itself over and over for millennia.

One of the differences that arose along the way involved the sound [n] which sometimes appeared and sometimes did not appear in certain words. This difference might be present and absent in the words of one language. The past participle of Latin frangere "to break", with an [n], was fractus "broken", with contained no [n] even though the present tense forms did. We see the same in frangere "to break" and fractus "broken", source of English fracture.

Sometimes we find the [n] in some languages that came from PIE but not in others. In English the word for "5" is five without an [n] but in closely related German, we find fünf, with one. The important point is that, as languages split up into dialects that became languages that split up into dialects, for reasons we don't understand, the sound [n] sometimes dropped out of words.

The same is true of the sound [s] at the beginning of words. It usually comes and goes from language to language. English tended to retain initial [s] before consonants in words like spin, while Latin tended to lose them, as in related word pendere "to hang". We see them same relationship in English slack and Latin laxus "loose" [læk-s]. Believe it or not, skald and cold developed from the same original root with and without the Fickle S.

In the Good Word series we call these two phenomena "Fickle N" and "Fickle S" because you can't depend on them to stay where they belong.

• The alphaDictionary Glossary of Rhyming Compounds (in alphabetical order)
• The alphaDictionary Glossary of Rhyming Compounds (by category)
• The alphaDictionary Rebel-Yankee Test has been enjoyed by more than 3 million people. See what all the excitement is about.
• Dr. Goodword's Glossary of Quaint Southernisms. If you enjoyed the Rebel-Yankee test, you will probably enjoy these linguistic differences between North and South.
• Dr. Goodword's Mini Linguistic Course. Learn the basics of language from a professor of linguistics in an hour.
• Dictionaries, Glossaries, and Word Lists. Lists of words that are problems to spell, pronounce, and remember—all by a widely published and respected specialist.
• Discuss accents and dialects with others. Now you can talk with others who have taken our test about your accent and theirs. You might want to talk about other topics, too, at our Alpha Agora.
• While you are here, check out our daily "So What's the Good Word?" feature. We select an interesting word and tell you all about it - how to say it, what it means, where it comes from, and how to use it. You can have it delivered to your email inbox daily, for free!