Many of us either have words that we confuse or get annoyed when someone else confuses a pair of words. Sometimes the words are very closely related. That we spell them slightly differently has little to do with their root meaning. Here are some of the word pairs that confuse or bother readers of this site. (They are not mine.)

List your own problem pairs of words

1. Loath and Loathe

   I always feel annoyed when I read a new book and the editor(s) obviously couldn't tell the difference between "loath" and "loathe" - one means "reluctant", while the other implies complete disgust.

   
   Loathe 'detest' and loath (loth) 'reluctant', come from the same Old English root word, lað 'hostile'. Etymology Online says the weakened use of loath (no-e) meaning 'averse' or 'disinclined' is first attested in 1374; however, loathsome (again, no e) means detestable. In meaning, loathsome is more like the verb loathe (with an e) than loath (no-e). To me, this confusion seems easy to make and hard to break, but then there is not a Latin or Greek root here for me to grab mental hold of.
   

1. Capital or Capitol

   I always thought I had them straight, but "Capitol" as a noun refers to the building housing a government's business affairs, while "Capital" as a noun, can be the city which houses the Capital (among other definitions); this according to Dictionary.com. I'd call this "capital confusion."

   
   Capitol (the building) comes from the Roman temple of Jupiter Optimus Maximus on the Capitoline Hill. Capital comes from a Latin adjective (capitalis) based on the Latin noun for head (caput). This capital (with an a) is used before 'letter' and describes the main city in a country/state.
   
   The name of the Roman Hill, Capitoline, may be connected etymologically with caput.
   
   Something related that confuses me is the capital used in describing a column. Columns were a major part of the ancient temples, so the Capitoline temple had columns and these columns had capitals. I need to remember that the capital refers just to the top (or head) of the capital.
   
2. Who's my Pal?

   For some reason, I can never remember if it's principle or principal. This got even more embarrassing when I married the son of a principal (or is that principle? **grin**). I think it was because when I was in school, the principal was never my "pal" so that mnemonic never really worked for me.

   
   Principal (your so-called pal in the school sysytem) comes from the Latin principalis 'first in importance', from princeps 'chief, prince'. Principally 'in the first place' comes from the same word. Principle (as in those things one always wishes politicians had) also comes from princeps 'chief, prince', but through the intermediary Latin form of principium 'beginning, first part'. So one's pal, the person, comes from the adjectival form, while the abstract comes from the nominal form.
   

1. Paper or Fixed?

   I always have trouble with stationary and stationery. I know one means writing paper and the other means fixed in place, but I have to think to figure out which one is which!

   Stationary and stationery are both derived from the Latin word statio 'standing, position, job'. Stationary comes more directly from the Latin adjective stationarius 'of a military station'. Stationary is like a soldier standing (stationary) and saluting. Stationery -- the writing paper -- comes from stationarius 'stationary seller', which doesn't help with the English spelling issue. As distinguished from a traveling peddler, the stationary seller worked in a fixed location. Since he worked at a station, he was a station-er (an agent ending).

How Do You recognize the Root?

Affect vs. Effect

I.e. vs. E.g.Also see these articles on words and word derivations:

• Latin Words in English I
  English has lots of words of Latin origin. Some of these words are changed to make them more like other English words -- mostly by changing the ending (e.g., 'office' from the Latin officium), but other Latin words are kept intact in English. Of these words, there are some that remain unfamiliar and are generally italicized to show that they are foreign, but there are others that are used with nothing to set them apart as imported from Latin. Here are some such words and abbreviations.
• Latin Words in English II
  (See preceding.)
• On Translating Latin Into English
  Whether you want to translate a short English phrase into Latin or a Latin phrase into English, you can not just plug the words into a dictionary and expect an accurate result. You can't with most modern languages, but the lack of a one-to-one correspondence is even greater for Latin and English.
• Latin Religious Words in English
  If you want to say that the prospects are bleak, you could say "it doesn't augur well." Augur is used as a verb in this English sentence, with no particular religious connotation. In ancient Rome, an augur was a religious figure who observed natural phenomena, like the presence and location to left or right of birds, to determine whether the prospects were good or bad for a proposed venture. Find out about more such words.