A few days ago when walking across campus I remembered Rome. This happens from time to time. In this case I thought particularly of the Campo de’ Fiori — the Field of Flowers — which in turn made me reflect that the word campus is just Latin for “field”. I had not noticed that before. I mentioned as much to my wife, and she remarked that the words company and companion were perhaps also related, and considering that each has a vaguely military connection she speculated that campus might have originally meant something like “field of battle”. Not to be left out, our daughter interjected with “Gaa!” At that, I gave thanks for them both, and I resolved to look into the matter further when I had access to a good dictionary.
Once home I hauled out the OED, cracked it open, and blew the dust from the musty, time-worn pages. Sure enough, campus means “field”. Interestingly, the word’s first recorded use was as late as 1774, when it was used to describe the grounds of Princeton University. “Having made a fire in the Campus, we there burnt near a dozen pounds [of tea].” (From the beginning, it seems, the university campus was a place of wild debauchery.)
It is probably not surprising to learn that campaign is a related word, which we have borrowed from French, where it also meant “field” or “countryside”. Its military sense derives from the fact that armies used to “take the field” for training and operations. Its political sense intimates that those seeking political office should be “put out to pasture”.
The word company, however, appears to have a separate etymology. Both it and companion come from Latin (com-panis) via Old French (compaignon), meaning someone with whom (com-) one shares bread (panis).
You are probably thinking that campanology, campaniliform, and similar words must also be related. However, these are derived from the Latin campana (bell), and I have been unable to discover a connection with our word of the day.