acute accent

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A mark (´) indicating:
2. n. that a vowel is close or tense, as é in French été.
3. n. that a vowel or syllable has a high or rising pitch, as in Chinese or Ancient Greek.
4. n. that a vowel is long, as in Czech dobrá.
5. n. that the syllable in which the vowel appears is stressed, as in Spanish fácil.

Wiktionary

1. n. orthography : A diacritical mark ( ´ ) that can be placed above a number of letters in many languages of the Latin, Greek and Cyrillic writing systems.

WordNet 3.0

1. n. a mark (') placed above a vowel to indicate pronunciation