Q: When is it correct to use the word "farther" as opposed to "further"? Both words seem to fit grammatically when used in a sentence such as, "We get thirstier the farther/further we hike." — Seth Chizeck, Pittsburgh, Pennsylvania

A: Perhaps I can provide a cool drink from the spring of knowledge.

Although "farther" and "further" were both originally comparatives of "far," they've taken on different meanings. In general, "farther" refers to physical distance, e.g., Let's go farther up the mountain; Moscow is farther away than Miami. "Further" is used for figurative distance, e.g., Let's carry this argument no further; We'll look further into the matter.

Full disclosure: A reader once scolded me for writing that Minnesota lies "further" north than Connecticut. Well, at least I got the geography right.

So, it's "farther" for physical distance and "further" for figurative distance. As your sentence about hiking involves physical distance, use "farther" and tell "further" to take a hike.

And, in case you're wondering, when terms such as "road" or "path" are used in a figurative sense, "further" should be used, e.g., Let's travel further down this road of self-discovery.

Q: Is this the way to render the plurals of single letters, e.g., She had no i's to dot or t's to cross? — Klaus Ebeling, Adams Center, New York

A: Yes. The plurals of single letters are formed by adding an apostrophe and an "s," e.g., the three R's, all A's on his report card, mind your p's and q's. (While single letters are placed in quotation marks, e.g., He wrote a "t," plurals of letters are not placed in quotation marks, e.g., He wrote two t's.)

When it comes to forming the plurals of multiple letters, acronyms and abbreviated words, things get tricky. Most usage guides and stylebooks follow these rules:

For plurals of abbreviations with no internal periods, add an "s" but no apostrophe, e.g., two IOUs, four URLs.

For plurals of abbreviations with internal periods, add an apostrophe and an "s," e.g., two Ph.D.'s, three M.B.A.'s.

For plurals of abbreviations that end with periods but have no internal periods, add an "s" but no apostrophe, e.g., two paras., three hwys. But if such an abbreviation is a unit of measurement, no "s" is added, e.g., 2 in., 3 gal.

To help me remember these complicated rules, I keep this sentence taped to my desktop computer:

Two M.D.'s and their assocs. told three VIPs to drink 4 qt. of water, catch some z's, and hike no further ... er, farther.

Rob Kyff, a teacher and writer in West Hartford, Connecticut, invites your language sightings. His new book, "Mark My Words," is available for $9.99 on Amazon.com. Send your reports of misuse and abuse, as well as examples of good writing, via email to [email protected] or by regular mail to Rob Kyff, Creators Syndicate, 737 3rd Street, Hermosa Beach, CA 90254.

Photo credit: susannp4 at Pixabay