The old LP, The Tartan, Scottish songs by Kenneth McKellar, has a fine version of this old song. I will dig it out and post more words (some are Gaelic, I can't reproduce those and they are Greek to me). A shieling is either a pasture (meadow) or a hut by the pasture. Sheeling, shealing, etc. etc. are all spellings that have been used. It is a very old word, 16th Century definitely but probably much older.