Elderly or aged
Fossil is a synonym of old and antique and begins with an F.
The answer to that question, what is the synonym of old?, is worn out. new
old, getting on, grey, ancient, antique, elderly
old fashioned
a synonym for eldest is oldest or old because the saying always respect your elders
Old man's beard.
expired or old
ancient, aged, old
old-fashioned
Aged, elderly & senior are all synonyms for old.
unusual, extraordinary, old-fashioned
dated, antiquated, outdated, old