I plan a chapter in Undecorated Buddha on how to translate Buddhist texts from Sanskrit without sounding like a total goon on bhang, but in the mean time trying to write clearly about Buddhism presents an interesting and sometimes annoying problem: lots of the technical terms have become loan words in English, and those loan words are usually very bad translations of the real term.
The worst of these, I think, is karma. We're used to the word, and most people understand it to mean something like "fate." If you asked in any rec center Yoga class, someone would undoubtedly talk about how your karma follows you from incarnation to incarnation, and bad things that happen to you now are because of some "evil karma" you picked up in a previous life.
This whole understanding of karma is really a sort of mashup of some Hindu concepts, and some ideas from Jainism, but even then it's a very unsophisticated view, sort of like the Christian picture of Heaven as a place where you sit on clouds playing harps.
The word, however, is very practical; it means "action". It's paired with vipaka which means "consequences."
You can understand karma and vipaka in terms of a pool game. You start a pool game with the 10 pool balls arranged neatly in a triangle. One player hits the cue ball into that triangle, and they scatter -- a "break".
If you watched in slow motion, you'd see the cue ball start moving from the way the cue strikes it. The cue striking it is karma; the way the cue ball moves is vipaka. Then the cue ball hits the racked pool balls, and that's karma; the ball or balls it hits start to move -- vipaka -- and hit other balls in turn -- karma. The moving balls interact with the felt -- karma -- and slow, as well as not following an exactly straight line because of spin and irregularities in the tabletop -- vipaka.