An abridged version of a book is a shortened version: it's not complete because parts have been cut or omitted.
Sometimes you have time to read all of something, but other times you don't. When you need to save time, you might need to look at an abridged version of a book. This is also called the "Reader's Digest version" of something, because that magazine publishes many abridged pieces. Reading an abridged text may save time, but don't kid yourself: the stuff left out was important too. If you really like an author, forget the abridged version and read the whole thing.
adj (used of texts) shortened by condensing or rewriting
with parts removed
abridged to half its original length
(British informal) summarized or abridged
primarily temporal sense; indicating or being or seeming to be limited in duration