dɪˈfɪʃənt ɪnˈfɪə.ɹi.ə ɪnˈfɪɹ.i.ɚ ɪnsəˈfɪʃənt ˈlækɪŋ ˌsʌbˈstændɚd ˌsʌbˈstændəd inadequate in amount or degree a deficient education deficient in common sense lacking in stamina tested and found wanting falling short of some prescribed norm substandard housing of a quantity not able to fulfill a need or requirement insufficient funds