Basically, the directory that you are packaging into the jar is confusing the jar file in locating the main class file.
Instead if trying do the following :
/usr/lib/jvm/jdk1.7.0_07/bin/jar cf Dictionary.jar /home/user1/dir/Dictionary.class
i.e. package the class file specifically into the jar and then run:
/usr/local/hadoop/bin/hadoop jar Dictionary.jar Dictionary
It just works fine provided that you have a main function in your class called Dictionary.
The problem is when you package a full directory inside a jar then the jar also needs to be aware of the directory structure to locate the class file. For this, we need to have a well defined package hierarchy to define the class location. So, when you are packaging /home/hduser/dir/ into the jar, the jar is not aware of the location of the class file which is located deep inside this directory structure. For this you need to add a package name to your .java file according to the directory structure , for example home.hduser.dir and while running the hadoop jar command specify the class name with the package structure, for example home.user1.dir.Dictionary.