As everyone knows, words constantly take on new meanings. Since these do not necessarily, nor even usually, take the place of the old ones, we should picture this process as the analogy of a tree throwing out new branches which themselves throw out subordinate branches. The new branches sometimes overshadow and kill the old one but by no means always. We shall again and again find the earliest senses of a word flourishing for centuries despite a vast overgrowth of later senses which might be expected to kill them.
When a word has several meanings historical circumstances often, make one of them dominant during a particular period. Thus "station" is now more likely to mean a railway station than anything else; "speculation" more likely to bear its financial sense than any other. Until this century "plane" had as its dominant meaning "a flat surface" or "a carpenter’s tool to make a surface smooth", but the meaning "an aeroplane" is dominant now. The dominant sense of a word lies uppermost in our minds. Whenever we meet the word, our natural impulse is to give it that sense. We are often deceived. To an old author the word may mean something different.
One of my aims is to make the reading of old books easy as far as certain words are concerned. If we read an old poem with insufficient regard for the change of the dictionary meanings of words we won’t be able to understand the poem the old author intended. And to avoid this, knowledge is necessary.
We see good words or good senses of words losing their edge or more rarely getting a new edge that serves some different purpose. "Verbicide", the murder of a word, happens in many ways. Inflation is the commonest: those who taught us to say "awfully" for "very", "tremendous" for "great", and "unthinkable" for "undesirable" were verbicides.
I should be glad if I sent any reader away with a sense of responsibility to the language. It is unnecessary to think we can do nothing about it. Our conversation will have little effect, but if we get into print -- perhaps especially if we are leader-writers or reporters -- we can help to strengthen or weaken some disastrous word, can encourage a good and resist a bad Americanism. For many things the press prints today will be taken up by a great mass of people in a few years.