In JavaServer Pages (JSP) technology, a scriptlet is a piece of Java-code embedded in the HTML-like JSP code. The scriptlet is everything inside the <% %> tags. Between these the user can add any valid Scriptlet i.e. any valid Java Code.
In AppleScript, a scriptlet is a small script.
In Windows, a scriptlet is COM component including a HTML code and a script which may be written in a variety of scripting languages.
References
Scriptlet Wikipedia(Text) CC BY-SA