Source : WordNet®

applet
     n : a Java application; an application program that uses the
         client's web browser to provide a user interface

Source : Free On-Line Dictionary of Computing

applet
     
         A {Java} program which can be distributed as
        an attachment in a {World-Wide Web} document and executed by a
        Java-enabled {web browser} such as Sun's {HotJava},
        {Netscape Navigator} version 2.0, or {Internet Explorer}.
     
        Navigator severely restricts the applet's file system and
        network access in order to prevent accidental or deliberate
        security violations.  Full Java applications, which run
        outside of the browser, do not have these restrictions.
     
        Web browsers can also be extended with {plug-ins} though these
        differ from applets in that they usually require manual
        installation and are {platform}-specific.  Various other
        languages can now be embedded within {HTML} documents, the
        most common being {JavaScript}.
     
        Despite Java's aim to be a "write once, run anywhere"
        language, the difficulty of accomodating the variety of
        browsers in use on the Internet has led many to abandon
        client-side processing in favour of {server}-side Java
        programs for which the term {servlet} was coined.
     
        Merriam Webster "Collegiate Edition" gives a 1990 definition:
        a short application program especially for performing a simple
        specific task.
     
        (2002-07-12)