In this narrow sense of the word, the first true alphabet was the Greek alphabet, which was based on the earlier Phoenician abjad.
ɪn ðɪs nˈæɹoʊ sˈɛns ʌvðə wˈɜːd, ðə fˈɜːst tɹˈuː ˈælfəbˌɛt wʌzðə ɡɹˈiːk ˈælfəbˌɛt, wˌɪtʃ wʌz bˈeɪst ɔnðɪ ˈɜːlɪɚ foʊnˈɪʃən ɐbdʒˈæd.