ɪn ˈʌðɚ wˈɜːdz, ðə sˈɛt ɪz fˈʌŋkʃənəli kəmplˈiːt ɪf ˈɛvɹi bˈuːliən fˈʌŋkʃən ðæt tˈeɪks æt lˈiːst wˈʌn vˈɛɹɪəbəl kæn biː ɛkspɹˈɛst ɪn tˈɜːmz ʌvðə fˈʌŋkʃənz fˈaɪ.
In other words, the set is functionally complete if every Boolean function that takes at least one variable can be expressed in terms of the functions ƒi.