Usage: "I would not like to eat that pie as it looks all festy since you dropped it on the ground."
Is the colloquial Australian term 'festy' actually a word?
Also, is it used elsewhere in the world?
The Merriam Webster hasn't heard of it, but the Urban Dictionary lists it with the first two senses as back-constructions of "fester", respectively:
As English seems to expand much more than it contracts, it seems that in another decade or so if not less, Webster will list it and then Oxford.
It's an Australian word formed by the addition of "y" to the contraction of fester.