Meaning : So extremely old as seeming to belong to an earlier period.
Example :
A ramshackle antediluvian tenement.
Antediluvian ideas.
Archaic laws.
Synonyms : antediluvian, antiquated
Meaning : Little evolved from or characteristic of an earlier ancestral type.
Example :
Archaic forms of life.
Primitive mammals.
The okapi is a short-necked primitive cousin of the giraffe.
Synonyms : primitive