One of two heard in America

• "A" as in "autumn"
• Sound heard twice in "Aruba"
• It's not a sign of stress
• Unstressed vowel symbol
• The "a" sound in "above"
• Inverted "e" phonetic symbol
• Phonetician's symbol
• The "a" sound in "afire"
• Stress-free vowel

Wiktionary Word definitions in Wiktionary
n. 1 An indeterminate central vowel sound as the "a" in "'''a'''bout", represented as /ə/ in IPA and /@/ in SAMPA and X-SAMPA. 2 The character ə, an upside-down, backwards, lower-case E