An error I often see in my students' papers and sometimes even in newspaper and magazine articles is the use of "upmost" where the word "utmost" is wanted. I recently came across this comment on a political message board: "The people in power in Bush's administration are the ones who are responsible for the torture of Iraqi prisoners at Abu Ghraib. Therefore, they should be punished to the upmost extent of the law.
The word wanted there is, of course, "utmost." This word comes from the Middle English word utmest, which itself comes from the Old English utmest. The Old English adverb
ut means "out," and mest is the ancestor of our word "most." "Utmost" (or "outermost") is a superlative, meaning situated at the farthest, most distant point. Thus it designates the extreme, the greatest or highest degree. This idea, of the highest degree, is probably what leads to the erroneous use of "upmost" in this sentence.
The word "upmost" is actually a form of "uppermost," and it does not fit into the same sort of sentence that calls for "utmost." In fact, you will seldom find it at all in modern American usage, though I do not know whether that form is still common in British English.
"Uppermost" means in the highest or most prominent position, power or rank,
~Uppermost in his mind were the risks of doing business with such a crook.
~The sweetest fruit was found in the uppermost branches.
In other words, be careful not to use "upmost" (position) when you mean "utmost" (degree), and if you should decide that "upmost" is the word you actually need, you should probably consider substituting the more commonly used "uppermost."