We don't have synonyms for ageisms yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are ageism and ageists.
(n) :
The treating of a person or people, especially older people, differently from others based on assumptions, prejudices or/and stereotypes relating to their age.
(n) :
The treating of a person or people, especially older people, differently from others based on assumptions, prejudices or/and stereotypes relating to their age.