Shades of meaning: Five commonly confused word-pairs

Vladimir Nabokov once said, “A writer should have the precision of a poet and the imagination of a scientist.”
The need to say exactly what you mean in written and spoken communication seems obvious, but when it comes to some of the English language’s most similar word-pairs (“big” and “large,” and “sure” and “certain,” for example), the subtleties are difficult even for grammarians to untangle.
Most of the world’s prominent grammarians have reached consensus for the appropriate uses of many often-confused word pairs. I explore the details of many of these grammatical errors in The Big Ten of Grammar and am sharing the grammarian’s official verdict on the usage of five commonly confused word-pairs.
“Sure” and “certain”
Both are used to express no doubt about something, but they used differently depending on how one concludes that there is no doubt.
“Sure” is used to express one’s belief of no doubt through intuition or feeling: “I am sure she loves me” or “I am sure we will get the apartment we want” or “I’m sure my life is going to get better.”
“Certain” is used when one’s conclusion of no doubt is based on facts, evidence, or definite grounds of some kind: “After reading the police report, I am certain the man is innocent” or “My research makes me certain my theory is correct” or “After studying the minutes, I am certain the city council made the right decision.”
“Less” and “fewer”
The traditional uses of “less” and “fewer” are being increasingly ignored.
Except in mathematical equations where numbers are defined as being “less than” or “greater than” other numbers, “less” should be used to refer to bulk or a general quantity, while “fewer” should be used to refer to individual items or to a number, to something that can be counted.
“I spend less time shopping in traditional stores, and I expect what I buy online to be shipped in fewer than three days.” “School begins in fewer than three weeks.” “Express Lane–fewer than 15 items.” “Fewer” than fifteen people applied for the job.” “I have fewer customers this year and less money.” “Having less business means needing fewer trucks.” “I advertised less and ended up with fewer customers.”
“Further” and “farther”
The interchangeable use of “further” and “farther” was first used in the Middle English period, the twelfth to the fifteenth century. The two words continued to be used interchangeably until about seventy-five years ago. Since then they have been thoroughly vetted by grammarians and are now uniformly used in similar, but slightly different, ways.
“Further” is used to indicate time, degree, or quantity (no notion of distance is indicated): “I need to look into the matter further before making a decision” or “My research needs to go further before writing the report” or “This investigation needs to go further than previous ones.”
“Farther,” on the other hand, is used to indicate distance: for example, “Bill ran farther than Joe,” or “Chicago is farther from St. Louis than Kansas City is” or “The next service station is farther down the road.”
“Big” and “large”
“Big” is a Scandinavian word originally meaning important or of great significance: “big deal” or “big man” (important leader or government office holder, officer in an organization or company). “Big” is now used to refer to something that is big in size or importance, but not humungous or terribly out of proportion.
“Large” comes from the English and French. Originally it was used in the sense of extravagant, lavish, exuberant, or lush and was considered an undesirable characteristic. “Large” gradually has come to refer to something that is very considerable in size or importance–out of proportion or overly large–but not necessarily an undesirable characteristic.
“Large” is generally thought of as being much greater and more comprehensive than “big.” Deciding which to use requires making a judgment call as to just how big or large something is.
“Often” and “frequently”
About sixty-five years ago distinguishing between the uses of “often” and “frequently” was given a great deal of attention in England. In the United States, however, until a few years ago, little attention was paid to the meanings of the two words, and they were used interchangeably. Now, grammarians in the United States have gotten on board, and grammatical standards for using “often” and “frequently” have taken root.
“Often” is used to indicate something happening many times, repeatedly, time and again–the expected norm. “Frequently” encompasses the same things as “often” and adds to it the idea of the expected norm happening at short or rapid intervals.
The bottom line is this: there is a subtle difference in how these two words are used, and it takes a discriminating judgment call to determine how frequently something happens.