Cofusing Words

AFFECT or INFLUENCE

I. VERB

• To have an influence on or effect a change in: Inflation affects the buying power of the dollar.
• To act on the emotions of; touch or move.
• To attack or infect, as a disease: Rheumatic fever can affect the heart.

II. NOUN

• Feeling or emotion, especially as manifested by facial expression or body language: “The soldiers seen on television had been carefully chosen for blandness of affect”.
• Obsolete. A disposition, feeling, or tendency.

III. SYNONYMS

affect, influence, impress, touch, move, strike.

These verbs mean to produce a mental or emotional effect.

- To affect is to act upon a person's emotions: Adverse criticism of the book didn't affect the author.

- To influence implies some control over the thinking, actions, and emotions of another: “Humanity is profoundly influenced by what you do” .

- To impress is to produce a marked, often enduring effect: “The Tibetan landscape particularly impressed him”

- To touch usually means to arouse a tender response: “The tributes [to the two deceased musicians] were fitting and touching”

- To move suggests a profound emotional effect: The account of her experiences moved us to tears.

- To strike implies keenness or force of mental response: I was struck by the sudden change in his appearance.

IV. USAGE NOTE

Affect and effect have no senses in common. As a verb affect is most commonly used in the sense of “to influence” (how smoking affects health). Effect means “to bring about or execute”: layoffs designed to effect savings. Thus the sentence These measures may affect savings could imply that the measures may reduce savings that have already been realized, whereas These measures may effect savings implies that the measures will cause new savings to come about.

Confusing Words

WHILE VS WHILST

You’re close to the target with your second example. Another pair of a similar kind is among and amongst (a third pair, again and against, has a similar origin but the sense of the words has since diverged).

In both cases, the form ending in -st actually contains the -s of the genitive ending (which we still have today, though usually written as ’s, of course). In Middle English, this was often added to words used as adverbs (as while became whiles, which often turned up in the compound adverbs somewhiles and otherwhiles). What seems to have happened is that a -t was later added in the south of England through confusion with the superlative ending -st (as in gentlest).

Both while and whilst are ancient, though while is older. There’s no difference in meaning between them. For reasons that aren’t clear, whilst has survived in British English but has died out in the US. However, in Britain it is considered to be a more formal and literary word than its counterpart. I have a small weakness for it, for which I’ve been gently teased in the past.

MISTAKE OR FAULT

Fault is often associated with the idea of blame. You have done something wrong and you are responsible for this/you are to blame for this and it is your fault.Mistake is usually used in connection with apology. If you make a mistake because you've made the wrong decision, you accept that you have done something wrong and you apologise for it.

Error is often connected to the idea of something being incorrect. You can choose the wrong word in a sentence. You press the wrong key on the keyboard and your computer shows that this is wrong and the word error appears on the screen.

Faults

Fault is not so much used to talk about someone’s character, Helen. Instead we talk about electrical, mechanical or technical faults:

There was a fault in the wiring and I had no idea how to correct it.There was a delay in the broadcast of the programme and this was due to a technical fault.
A mechanical fault caused the train to come off the rails.

A fault then describes a weakness in something, primarily. But sometimes it is used to describe a weakness in someone’s character:

- She has her faults, but, on the whole, she’s a nice person.
- We all have our own faults, I suppose.

We also have the frequently used expression: It’s (not) my/your/his/etc fault. This is a more idiomatic way of saying: I am (not) to blame or I am (not) responsible (for this unfortunate situation).

- It’s not my fault he’s late. Don’t blame me.
- I’m sorry. It’s my fault. I forgot to pass on the message.
- If you don’t get enough sleep, it’s entirely your own fault.
- It was partly the teacher’s fault for giving them too much homework.