exocentric & endocentric (in our Linguistic Book)

Our Linguistic Book said the typical form of excentric is preposition phrases ,while the typical form of endocentric is noun phrase .But I'm stlll not quite understand what is excentric and endocentric.

[Tdol]

http://dictionary.reference.com/search?q=excentric

http://dictionary.reference.com/search?q=endocentric

Originally Posted by tdol

http://dictionary.reference.com/search?q=excentric

http://dictionary.reference.com/search?q=endocentric

Thanks.

But it is too simple

[Tdol]

A lot of linguistics is fairly simple, but hides behind rather grand terms. Another difficulty is that many of the terms are confusing to the extent that they seem designed to make things more difficult for students than they need be.

[Francois]

You mean, like psychologists ? :)

FRC

[Tdol]

All of them. They also keep changing the terms, which is particularly irritating; is it the present continuous, progressive or durative?