نظير

In Arabic astronomical terminology, nazir al-samt meant 'opposite the zenith'—the point on the celestial sphere directly below an observer, through the earth and out the other side. Arab astronomers needed this concept for their calculations; the nazir was as important as the samt (direction) overhead. The word nazir itself meant simply 'opposite' or 'corresponding to.'

As European scholars translated Arabic astronomical works, nadir entered Medieval Latin and then vernacular languages. The word arrived in English by the 15th century, initially as pure astronomical terminology. Unlike zenith, which lost its Arabic article, nadir retained a form close to its original: the opposite point, the lowest position a celestial body could occupy relative to an observer.

The metaphorical extension came naturally. If zenith meant the highest point, nadir must mean the lowest. By the 17th century, English speakers used nadir for depths of despair, failure, or degradation. A nation could reach its nadir; so could a stock price, a reputation, or a mood. The astronomical term for 'beneath your feet' became the emotional term for 'as low as you can go.'

Today nadir is used almost exclusively as metaphor. Sportscasters describe a team's nadir; historians identify the nadir of race relations; critics pinpoint an artist's nadir. The Arabic word for 'opposite' has become English's most dramatic term for rock bottom—a word that looks down instead of up, measuring distance from the heights rather than from the ground.