Is there a way to rename menu items in Mac?
You will have to edit the .nib files with a text (or xml) editor. First make a backup of the app (especially for Finder), then go into the bundle contents and find the English.lproj or en.lproj. This will probably be in the Resources/ folder. 

Most likely, this file will be called MainMenu.nib. However, Finder's is MenuBar.nib and some apps, like Firefox, won't have one at all.

The nib file can be converted to XML with plutil -convert xml1&lt;filename&gt;. Then you can open it in the text editor of your choice. Just command ⌘+F (or control ⌃+S) for the menu name you want to change. It should look something like this:

&lt;string&gt;New Tab&lt;/string&gt;
&lt;string&gt;newSession:&lt;/string&gt;


Edit the string at the top. This is actually the Interface Builder connection between the menu item of that name and the Objective-C selector/method that it calls. Save the nib and relaunch the application (with Force Quit or killall for Finder) and you should have the different name showing up.