Executive Secretariat- Link to Home page
Link to NIH Staff Interaction with the Executive Secretariat
Link to Help with Writing Official Correspondence Link to Plain Language Initiative
Link to Reports & Meetings Link to NIH Key Staff Lists Link to About Executive Secretariat
Return to Previous Page Return to Home Page
Link to Help with Writing Official Correspondence
Guidance on Preparing Documents for the Secretary Style Guidelines for Official Correspondence Writing Basics Use of Specialized Terms, Abbreviations, and Acronyms On-line Writing Resources
Composition Frequently Misused Words Grammar Punctuation Style
Frequently Misused Words

Additional examples can be found at Commonly Confused Words and Common Errors in English.


Affect is generally a verb; effect is generally a noun. (See a dictionary for exceptions.)

Cigarette smoke affects my breathing.

Cigarette smoke has an effect on my breathing.

composed of/comprises

A medication may be composed of or may comprise a number of ingredients. A medication is not comprised of ingredients.


Always use as one word.


Ensure means "make certain."Essentially, insure and assure also mean "make certain,"
but insure implies taking precautionary measures and
implies removing doubt from someone's mind.


Use fewer when referring to a group of distinct elements,
less when referring to an aggregate:

Fewer people are dying of strokes.

Please use less vinegar in that dressing.

Fewer sugar cubes in your coffee means less sugar in your diet.


If specifies a condition,
whether introduces an indirect question concerning alternatives.

I do not know whether he can do it.

If he can do it, let him.


These two words are related but refer to different ends of the communication process. When speaking or writing, you can imply something beyond what your words state directly; the person listening to you or reading what you have written can then infer your indirect message.


Lay (past tense and past participle form, laid) is a transitive verb; people lay things on the table or floor.
(past tense, lay; past participle, lain) is an intransitive verb; things and people lie on the table or on the couch.

Mary laid the sweater on the chair.

The sweater is lying on the chair.

Please lay your books on the table.

John is lying on the couch.


Yesterday, John lay on the couch all afternoon.
(The simple past tense of lie is lay.)



Actually, NIH is rarely misused on campus, but this entry is provided as a reminder that NIH is singular, and that NIH takes the definite article the when the sense of the sentence demands it.

The NIH is sponsoring a symposium.

Please adhere to NIH guidelines.

not only ... but also/as well

Always use not only in conjunction with either but also or as well.

Jim bought not only a computer but also a new desk.

Sheila sent her complaint letter not only to the company but to the newspaper as well.


Principal can be either a noun or an adjective, meaning either a person in authority or a person or thing of primary importance. Principle is always a noun, usually referring to a fundamental rule, characteristic, or ingredient.

philosophical principle

principal of a school

principal parts of a verb:

interest earned on the principal in a savings account

principal investigator

underway/under way

Underway is a rarely used adjective; under way is a commonly used adverbial phrase.

Some aircraft are capable of underway refueling.


Some aircraft are capable of refueling while under way.

The meeting is under way.


Which always follows a comma and introduces a nonrestrictive clause. A comma does not precede that, which always introduces a restrictive clause.

Cotton candy, which always makes me sick, is one of my weaknesses.

Cotton candy that is red always makes me sick.

In the first example, the clause is nonrestrictive because it refers to all cotton candy; in the second, the clause is restrictive because it describes a specific cotton candy.

Go Back Go to Top

Last updated: April 17, 2003