The meaning of knife, unlike that of spoon or fork, has not varied since it was first recorded in English in the eleventh century. Its spelling and pronunciation, however, have changed significantly. From the eleventh to the thirteenth centuries the word was spelt cnif, with the initial c being pronounced like a k, and with the i in the middle being pronounced as a short vowel to rhyme with sniff. By the fourteenth century, though, the spelling had been changed to knyf, thanks to a modified spelling system introduced by the French after the Norman Conquest; the k sound of knyf continued to be pronounced for another century until it fell silent in the fifteenth century; about the same time it started to be regularly spelt as knife. Given that tape recorders were still centuries away, how can you tell when the k sound in words like knife, knight, knee, and knuckle were dropped? You can tell by the appearance of literary puns that had never before been made. Chaucer, for example, writing in the late fourteenth century, never makes a pun out of knight/night because he pronounced the two words differently; Shakespeare, however, writing in the late sixteenth century, does pun on knight/night because for him, like us, the words were homonyms.