adjective Belonging or pertaining to, or existing in, the time prior to the great flood described in Genesis, or to a great or destructive flood or deluge described in other mythologies.
adjective Of animals and plants: long extinct; prehistoric.
adjective Of a person or thing: very old; ancient.
Those ideas are antediluvian.
adjective Of a person or thing: very old; ancient.
adjective Of attitudes, ideas, etc.: extremely old-fashioned, especially to a laughable extent; antiquated.
Those ideas are antediluvian.
noun A person who lived in the time prior to the great flood described in Genesis, especially one of the biblical patriarchs.