We don't have synonyms for tea gowns yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are tea gown, sea gown and teardowns.
(n) :
Alternative form of tea-gown. [A loose-fitting semiformal gown, made of light fabrics, worn in the late 19th and early 20th century for entertaining, especially for afternoon tea.]
(n) :
Alternative form of tea-gown. [A loose-fitting semiformal gown, made of light fabrics, worn in the late 19th and early 20th century for entertaining, especially for afternoon tea.]