Diacritic

A diactric mark, such as the cedilla of façade or the acute accent of résumé, added to a letter to indicate aspecial phonetic value or distinguish words that are otherwise graphically identical.

A diacritic is a an additional sign (within a given dialect) that is added to a given letter, primarily in order to provide greater insight about how that letter is to be pronounced. 

Some of the most common kinds of the diacritic are often called accent marks, in popular parlance. These marks are used to indicate which syllable of a given word the spoken stress should fall upon. 

The diacritic is far more significant a part of some written languages than other written languages. For example, it is highly prevalent within Spanish, while not all that prevalent at all with English. 

Basic rules of diacritics

The basic rule for the use of a diacritic is that it is included within the spelling of a word in the event that the proper pronunciation of a word is counterintuitive on the basis of its spelling. That is, if the spelling of the word would contradict normal pronunciation rules within a given language, then the diacritic shows how the pronunciation ought to be changed. 

Some of the most common diacritics include: 

1. the acute (small apostrophe-like dash over a letter), which indicates that the given syllable within the word is the one that should be stressed when spoken; 

2. the cedilla (small curved dash under a c), which indicates that the c is to be pronounced as an s and not as a k;

3. the umlaut, (double dot over a vowel), which indicates either a change in vowel pronunciation or a syllable break; 

4. the tilde (squiggly line over an n), which indicates that the n is supposed to pronounced as a "nye". 

The acute can be found in the word saké; the cedilla can be found in the word façade; the umlaut can be found in the word Noël; and the tilde can be found in the word piñata. 

Use in English language

Many forms of the diacritic within English writing are borrowed from other languages. For example, the cedilla is primarily French, the umlaut is primarily German, and the tilde is primarily Spanish. Likewise, these forms of the diacritic usually appear with English writing in words that have been borrowed from those other languages.  

The acute diacritic, though, has a long history within English literature. This is due to the fact that this diacritic can be used in order to indicate that the final vowel of a word is to be actually pronounced and not just passed over. This also alters the syllabic count of the given word, which can be relevant for the composition of metered poetry. For example, the word "breathed" may not fit within the syllabic structure of a sonnet, whereas the word "breathéd" would.

Moreover, the umlaut diacritic can be useful for indicating syllabic breaks in English words. For example, some publications spell coordination as coördination, in order to indicate that there is a break between the two o's. 

In general, though, the diacritic would seem to be more important in other languages than it is in English. For example, the acute diacritic is almost omnipresent in Spanish writing, due to the fact that Spanish has a highly regular spelling structure: it is always necessary to indicate where a stress is in fact supposed to fall, if it is to fall somewhere other than what would be expected according to standard spelling structure.