Defunct/dɪˈfʌŋkt/ Definition 1 of 3Pro Tip 1/3Ceased Operations Use 'defunct' for businesses or organizations that have stopped operating and dissolved. The airline went defunct after 50 years in business. Pro Tip 2/3Historical Context 'Defunct' can refer to practices or institutions that have become part of history. The feudal system is now defunct. Pro Tip 3/3Technological Shifts Use when technology advances make older versions useless or redundant. With the introduction of smartphones, pagers are largely defunct.