Exceptions and Errors are both derived from Throwable (in java.lang).
"Checked" exceptions are those for which the compiler enforces either declaration or handling. All subclasses of Exception -- other than RuntimeExceptions and its subclasses -- are checked. (See bold below.)
RuntimeExceptions (e.g., bugs resulting in a NullPointerException) and Errors, or subclasses of these, are not checked and do not need to be declared or handled.
"We're kind of on the level of crossword puzzle writers... And no one ever goes to them and gives them an award." ~Joe Strummer sscce.org
An Error is a subclass of Throwable that indicates serious problems that a reasonable application should not try to catch. Most such errors are abnormal conditions. The ThreadDeath error, though a "normal" condition, is also a subclass of Error because most applications should not try to catch it.
A method is not required to declare in its throws clause any subclasses of Error that might be thrown during the execution of the method but not caught, since these errors are abnormal conditions that should never occur.
Java Developer, Thailand
I think Steve is correct, it is not a word but a casual contraction. If you intention is to commmunicate, or to pursuade others to communicate with you I stongly urge you use complete words. Note that many, many people using these forums do not have English as a first language or even your particular version of English so for your own benefit in getting results, use a standardized English in technical communications.
When chatting with people U kno, U Can Uze eny variationz you like and you will be thort of as L33t d00d.