We don't have synonyms for sideling yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are sidelong, sideline and piddling.
(n) :
Archaic form of siding (“side branch of railway track”). [(Canada, US) A building material which covers and protects the sides of a house or other building.]
(n) :
Archaic form of siding (“side branch of railway track”). [(Canada, US) A building material which covers and protects the sides of a house or other building.]