To make foul or dirty, this instance of “be-” forms the verb out of the adjective “foul”. In the 13 and 1400s, this word slowly replaced “befile”, an interesting formation of be-defile.
- 13.043 and though all was befouled and blasted
I note that the filth that one is covered with when befouled often refers to metaphorical moral filth. All in this passage has been befouled by Smaug’s coming and goings – and also his malice? More on the malice of dragons in Legard.
“befoul, v.” OED Online. Oxford University Press, March 2015. Web. 7 May 2015.
Legard, Sara. “Essential Dragons Beyond Tolkien’s Middle Earth”. Mythmoot II Proceedings. Mythgard Institute. Web.