21. Error/mistake

The difference between the two is not enormous, but error is usually less serious than mistake. If I ask you to multiply 312 by 758, and you tell me that the result is 236 498, you probably made a slip when typing the last digit. I would call this an error. If you tell me that you bought a company two years ago, which has so far lost two million dollars, you made a mistake (How could you do such a thing?).

22. Every/each

Here is something for the connoisseur. Every applies to an unspecified number of objects. Each is usually better when the number of objects is known or small. Examples: In Glasgow you find a pub in every block. You do not know the number of blocks in merry Glasgow. You are making a general statement, therefore every. There is an entrance at each corner of the park. You know that the park has four corners. Therefore each. Here are two nearly identical sentences with a difference in interpretation: Every airliner has a Certificate of Airworthiness. All airliners have it. A general statement. Each airliner has a Certificate of Airworthiness. Each single aircraft I am talking about; presumably of one specific company, production run, type.

23. Exceptional/exceptionable

Exceptional is, of course, something that is an exception, unusual, abnormal: We had an exceptionally wet summer three years ago. Exceptionable is mainly used in the negative form unexceptionable. It means acceptable, not open to objection: I have read the conditions. They seem unexceptionable. To take exception to something means to disapprove, raise an objection. You will probably find exceptionally good weather unexceptionable.

24. Fast/quick

These two are not completely interchangeable. Fast refers to speed of movement or action: A fast train. A fast run. Quick relates to the length of time an event or action takes: A quick meal. A quick reply. Using both adjectives in one sentence, you could say: They had a quick crossing because the boat was fast. He had a quick meal because he is a fast eater. Exception department: quick can mean speed if the movement or action is not sustained, abrupt: Try to get that window seat! Quick! or He is an odd kind of man, with very quick, nervous movements.

25. Farther/further

Good news! Further can now safely be used in place of farther although there is a difference according to the dictionary. Farther is the comparative of far and thus relates to physical distance: London-Eastbourne is farther than London-Brighton. Nobody will be worried if you use further here. Further means additional, other, subsequent: We have to await further developments. Floor/storey (Am.: story) Floor indicates the position in a building: second floor, top floor, etc. Storey refers to the height of a building: a ten-storey apartment block.

26. Historic/historical

Historic refers to something important that is or will be remembered in history, recorded by history: a historic meeting, historic decision, historic voyage, historic landmark, etc. Historical is the adjective for all other purposes when you mean to do with history: a historical play, historical novel, historical costumes, etc.