Because the Earth wobbles on its axis, the celestial equator is over the terrestrial equator only twice a year, at the equinoxes when night and day are of equal length. The Sun is a nomad and for the first half of the year it tramps slowly southwards until it gets to a latitude of 23 degrees, at which point it turns around and heads for 23 degrees north, where it turns again.
The Greek for turn was tropos, which is why a turn of phrase was for them a rhetorical trope. That’s also the reason that the latitude of 23 degrees south is the Tropic of Capricorn and its northern equivalent is the Tropic of Cancer, and everywhere in between is tropical.
Bang in between the two tropics is the equator that runs like a 25,000-mile belt around the Earth.[6] The Spanish for equator is ecuador, so when they found a country through which the ecuador ran, they called it Ecuador.
The equator is called the equator because it divides the Earth into two equal sections, which therefore have equality. In most circumstances inequality is iniquitous, but sometimes iniquity is necessary. Not everybody can be equal. Take, for example, sport. You have two teams that have equal status, but when they argue you need somebody of higher status to judge between them. This referee is not on a par with them. In Latin he was a non-par and in Old French he was a noumpere, but then something happened to the N and he became an umpire.
An undignified fate often awaits words that begin with an N. Cooks used to wear a napron. But naprons were more often stained than written down, and so the A was able to craftily steal the N away from napron, and now a cook wears an apron.
This fickle N is something to ponder next time you’re bitten by a nadder, but I wouldn’t ponder it for too long.
Sometimes the inconstant N travels the other way. What was once an ewt is now a newt; and an extra name, an eke-name, is now a nickname.
The Latin par also gave us parity, peer groups, peerless and peers of the realm. It may seem rather odd that aristocrats, who are above everybody else, should be called peers. The reason is that Charlemagne had twelve noble knights who were all equal, and therefore peers. In fact, Charlemagne didn’t have twelve knights, but there was a legend that he did, and that’s quite good enough for spawning a word.
Par hides all over the place. If you do somebody down and make them feel less important than you, you disparage them; and if you have a girl to live with you as an equal she is an au pair. But the most obvious place that the word par survives is on the golf course, as the score between a birdie and a bogey.