E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Lang Syne (Scotch, long since).
In the olden time, in days gone by.
There was muckle fighting about the place lang-syne.Scott: Guy Mannering, chap. xl.
The song called Auld Lang Syne, usually attributed to Robert Burns, was not composed by him, for he says expressly in a letter to Thomson, It is the old song of the olden times, which has never been in print . I took it down from an old mans singing. In another letter he says, Light be the turf on the heaven-inspired poet who composed this glorious fragment. Nothing whatever is known of the author of the words; the composer is wholly unknown.