We don't have synonyms for old light yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are red light, cold light and old sight.
(n) :
(Christianity) A relatively traditional, conservative religious movement, especially (historical) the religious movement consisting of the seceders from the Church of Scotland who continued to hold unchanged the principle of the connection between church and state, the position maintained by the first seceders in 1733.
(n) :
(Christianity) A relatively traditional, conservative religious movement, especially (historical) the religious movement consisting of the seceders from the Church of Scotland who continued to hold unchanged the principle of the connection between church and state, the position maintained by the first seceders in 1733.