We don't have synonyms for siders yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are sider, sides and riders.
(n) :
Obsolete form of cider. [(British, Ireland, Australia, New Zealand, Canada) An alcoholic, often sparkling (carbonated) beverage made from fermented apples; hard cider; apple cider.]
(n) :
Obsolete form of cider. [(British, Ireland, Australia, New Zealand, Canada) An alcoholic, often sparkling (carbonated) beverage made from fermented apples; hard cider; apple cider.]