A circle of altitude, parallel to the horizon. An astronomical term, used to describe imaginary lines in the sky by which an astronomer determines the height of a star in the sky relative to the horizon.
From Arabic almuqantarat, the sundials.
Using his complex variety of looking glasses and odd devices, the scientist used several of the almacantar lines to calculate the height of two particularly interesting stars. By taking their relative distance from one another, and a form of complex calculations, he successfully managed to calculate the boringness of today's word usage. Eureka!