K is an odd letter in English. The sound represented by k is quite common in English, and in the related Germanic languages. But k itself is rare.
1066: The French win the Battle of Hastings and screw up Engllsh
spelling forever.
Exhibit A: Scrabble.
There's only
1 tile for K (of 100) in English-language Scrabble, but there's
2 K tiles (of 102) in German Scrabble. And Dutch, English's close relative, has
3 tiles (of 102) for
k, as do English's rather more distant relatives, Danish, Norwegian, and Swedish.
Why is the rather ordinary k so rare in English?
Confusion over C
When English was first written in the Latin alphabet, c was used for the k sound of spoken English, because that was how Latin was pronounced at the time. Latin had picked up k from the Greeks, but didn't use it much. Hence Caesar would be pronounced like the modern German Kaiser.
But then confusion arose in the Romance languages about how Latin c was to be pronounced, which spilled over into English. This got particularly bad after 1066 when the French-speaking Normans took over the country and got busy ruining, or improving (depending on your point of view) the English language with Francophone orthography.
In English, C came to be pronounced "hard" (like k) before the vowels a, o and u (e.g. candle, corn, cup) and "soft" (like s) before e and i (e.g. century, citizen). Because English was the only Germanic language to go through this change, K still carried the load in the other Germanic languages that was partly shifted over to C. This explains the relative profusion of k tiles in the Dutch and Scandinavian Scrabble editions.
K comes off the bench
But k still found a role in English. With c no longer exclusively representing the k sound, this left room for k to finally get some playing time, replacing c in some instances.
K became a silent marker in the ck digraph to show the "hard" pronunciation of c: back, block, clock, hack, lack, pack, rack, rock, sack, tick, wreck, etc. Exceptions exist of course for recently borrowed foreign words, slang, and trademarks, hence Anzac, Bic, bloc, magic, psychic, roc, tic-tac-toe etc.
K could also be used in medial position in lieu of c, particularly where a confusion might arise with a newer word. Hence macian came to be make making a clear contrast with the newer word mace. Other examples: bacan→ bake, haca → hake, saca → sake, slacian → slake.
Limits on K at the end of words.
English for some reason doesn't seem to like words that end in k unless preceded by either:
*a double vowel, hence beak, book, oak, peak, reek, wreak. Again, this seems to have arisen because of the uncertainty attached to the pronunciation of c, and the need to clearly identify the consonant sound. Hence boc → book, ac → oak, rec → reek
* another consonant, typically l, n, r, or s, for example: bilk, bank, desk, dank, dusk, frank, folk, hank, husk, milk, rank, tank, work
* exceptions exist, typically foreign words and neologisms, such as flak, yak and springbok.
K at the start of words
For K in initial position, there are few native words, as this sound was furnished by "hard" c. The few native words that begin with k appear to have shifted from their original c spellings, probably as as result of the influence of cognate words in Old Norse which were spelled with a k. (Native words that began with cw shifted to using qu, e.g. cwen → queen, but that's another topic.)
Some examples of Anglo-Saxon to modern English: cyrnel → kernel, cæg → key, cynn → kin, and (probably) cwellian → kill.
Words that start with kn are almost always native words, for example know came from cnawan. Originally both letters (cn or kn) were pronounced. On a side note, English is one of the few languages where a single word, know includes the meanings "to know a fact" and "to be acquainted with a person."
Foreign word origins.
Words in modern English are sometimes said to be of "native" and foreign" origin. Native words are simply those for which there can't be shown to be a time when the word was not part of the language.
But linguistic borrowing goes a long way back, and the k words provide strong evidence of this. Words that we now think of as basic to the language, such as mile turn out to have been introduced from Latin during the long course of the interaction of the Roman Empire with the Germanic tribes.
For example, kiln, which was present in early English as cyln or cylen came from Latin culina, meaning "kitchen" or "stove". Similarly, kettle was once spelled cetil, and came from Latin catillus, with the spelling shifting to an initial k probably because of the influence of the Old Norse cognate ketill.
It makes you wonder what kind of life the Germanic tribes must have been living 2,000 years ago if they had no native words for oven, kitchen or kettle.
Because of the rarity of k in native words in initial position (except for the kn digraph), k at the start of a word is a strong indication that is of foreign-origin or neologisms, for example, kahuna, karst, kindergarten, Kevlar, etc.
Political spin-offs
There are some uses of k that can generate highly emotional responses in English, such as the spelling of America as Amerika, This, being the German spelling, is tantamount to a being a comparison of the U.S. to a European dictatorship. As such it was commonly used by the radical left in the 1960s, and one sees it from time to time nowadays on far right websites now that Obama is president.
Handy links
* Scrabble dictionary: words that end in K
* Scrabble lookup: words that start or end in K
* Online Etymology Dictionary: K