I was trying to post the following, decide for yourself if you want to post it:

Because there are multiple ‘post offices’ in this country and throughout the world. There are many internets (networks linked together - ie Hoffman Estates campus is networked with Dekalb campus as well as the Naperville campus. But there is just one Internet that is commonly referred to that represents a specific noun. There are multiple electricity systems, there is a concept of a National Electric Grid. There are multiple sewer systems, but they are not typically referred to specifically.

A dictionary does not refer to a specific noun. The MS Word Dictionary (or Microsoft Word Dictionary) does.