>> It's 'aasavaa'. The word itself is pre-Buddhist and means a leak
>> through which defilements flow in.

>I had understood aasava to be an *outflow* rather than an inflow.

That is a question that I have been trying to find an answer to for a while.
Ajahn Maha Boowa (or at least the person writing his glossary) defines it as
"those defilements that flow out from the heart into thoughts, speech, and
action". If you look at the PED it also suggests the translation as
outfolows. It has:
1. spirit, the intoxicating extract or secretion of a tree or flower
2. discharge from a sore
So aasava, also in it's non-buddhist use, seems to have had the connotation
of outflow rather than inflow. And while I can still think of kaama and
bahava as inflows I have a hard time seeing avijja as something coming from
outside.
From the PED you can also see that it had (and also has in ayurveda as far
as I know) the meaning of intoxicant or fermentation, and Thanissaro Bhikkhu
translates it just like that (besides "effluents"). So it would probably be
something that was latent in the heart and fermented until it flowed out
"into thoughts, speech, and action" like the discharge from a sore.
Overall I would prefer a translation as either outflows, effluents or
inflows to anything other like cankers or taints, since it better renders
the way it is perceived. I come more and more to the conclusion that the
Buddha didn't use this certain terms without a reason and that there is some
deeper psychological significance to them, so I generally prefer to
translate them rather literally where possible.
Maybe somebody else has some more thoughts on this?

Greetings
Lars

P.S.: Maybe I should also introduce myself first :-)
My name is Lars Siebold and I am from Germany.
At the moment I am intensifying my studies in Pali a bit, as I became quite
curious about the real meaning behind all those translations (sometimes it
is really interesting how much more meaning it makes when you read the
Pali). However I have never properly managed to work through a textbook, so
at the moment I am doing some "lerning by doing".