fanum

The root fanum is one of those rare cases where a quiet, sacred word ended up describing screaming crowds and burning zeal. In Latin, fānum meant a temple — a consecrated, holy place set apart for a god. It was the calm center of religious life.

The drama begins with a derivative: fānāticus, meaning 'of or belonging to a temple,' and especially 'inspired by the temple.' This was not a compliment about piety. It described the temple servants who fell into ecstatic frenzy during certain rites — people who seemed possessed by the god, raving, trembling, out of their ordinary minds. To be fanaticus was to be in the grip of a divine madness. So even in Latin, the word already carried the charge of excess: not steady devotion, but devotion that has boiled over.

English borrowed this as fanatic, and the religious origin faded while the 'boiled-over' part stayed. A fanatic is now anyone whose enthusiasm has crossed into the extreme and uncritical — a religious fanatic, a fitness fanatic, a political fanatic. The adjective fanatical describes that same blind, excessive intensity, and fanaticism names the condition itself. (The casual word fan, as in a sports fan, is usually traced to this same fanatic — devotion, just dialed down to the friendly, harmless end.)

Now the mirror image. Take the temple, fānum, and put pro- in front, meaning 'before' in the sense of 'outside, in front of.' Profānus literally meant 'in front of the temple' — that is, outside the sacred enclosure, in the ordinary, non-holy ground. So profane came to mean 'not sacred, worldly,' and then 'disrespectful toward what is sacred' — to profane a holy place is to treat it as if it were just common ground. The sacred and the profane are the two halves of the temple's threshold: inside is fānum, outside is pro-fānum. From one holy building, English drew both the language of fevered belief and the language of irreverence.