Noun
a mark placed above a vowel to indicate pronunciation
Source: WordNet1. Traditional orthography as in Roman Catholic service books (stressed syllable marked with an acute accent on words of three syllables or more). Source: Internet
Diacritics Three kinds of diacritic were in common use: the acute accent ´, the grave accent `, and the circumflex accent ˆ. These were normally only marked on vowels (e.g. í, è, â); but see below regarding que. Source: Internet
Handwriting in Latin from 1595 The acute accent marked a stressed syllable, but was usually confined to those where the stress was not in its normal position, as determined by vowel length and syllabic weight. Source: Internet
Exceptions to those rules are indicated by an acute accent mark over the vowel of the stressed syllable. Source: Internet
For example, the acute accent may indicate a high tone, a rising tone, or, in the case of Chinese, any tone called "rising" (上) for historical reasons. Source: Internet
However café is now sometimes facetiously pronounced "caff", while in pâté, the acute accent is helpful to distinguish it from pate. Source: Internet