Dreimorengesetz is a German term which translates to "three-mora rule." This name is given to the rule for placing the accent in a Latin word.
With few exceptions, Latin words are stressed on the penult (second-to-last syllable) if it is "heavy" (having a long vowel or diphthong or ending in a consonant), and on the antepenult (third-to-last syllable) if the penult is "light" (ending with a short vowel.)
Examples:
( - marks a syllable boundary, • marks a mora boundary)
If one counts all "light" syllables as one mora and all "heavy" syllables as two morae, it becomes clear that the accent is essentially always placed three morae before the end of the word. Note, however, that for this analysis to work, one must always count the final syllable as one mora, regardless of its actual syllabic composition.
Examples:
5th mora | 4th mora | 3rd mora | 2nd mora | final | accent | |
---|---|---|---|---|---|---|
co | ń | di | tum | = cónditum | ||
co | n | dí | i | tum | = condítum | |
co | n | dú | c | tum | = condúctum |
A somewhat different, and possibly more accurate, analysis is to consider the final syllable as extra metric; then the accent always falls on the syllable with the penult metric mora, and there is no need to define a special type of mora counting for the last syllable.
Many other languages have similar but not identical rules for the placement of the accent: