Wordnet 3.0
NOUN (2)
1.
a hole (as in the wall of a building) made by rats;
2.
a small dirty uncomfortable room;
WordNet (r) 3.0 (2006):
rathole
n 1: a hole (as in the wall of a building) made by rats
2: a small dirty uncomfortable room
The Jargon File (version 4.4.7, 29 Dec 2003):
rathole
[from the English idiom ?down a rathole? for a waste of money or time] A
technical subject that is known to be able to absorb infinite amounts of
discussion time without more than an infinitesimal probability of arrival
at a conclusion or consensus. ?That's a rathole? (or just ?Rathole!?) is
considered a pre-emptive bid to change the subject. The difference between
ratholes and religious issues is that a holy war cannot be pre-empted in
this way. Canonical examples are XML namespaces and open-source licensing.