equatorial(n = noun.artifact) - a telescope whose mounting has only two axes of motion, one parallel to the Earth's axis and the other one at right angles to it;
is a kind of scope, telescope

1.  equatorial(a = adj.pert) - of or relating to or at an equator; "equatorial diameter"
Derived form noun equator₂

2.  equatorial(a = adj.pert) - of or relating to conditions at the geographical equator; "equatorial heat"

3.  equatorial(a = adj.all) - of or existing at or near the geographic equator; "equatorial Africa"
Antonym: polar
Derived form noun equator₁

   Of or pertaining to the equator; as, equatorial climates; also, pertaining to an equatorial instrument. [1913 Webster]

   An instrument consisting of a telescope so mounted as to have two axes of motion at right angles to each other, one of them parallel to the axis of the earth, and each carrying a graduated circle, the one for measuring declination, and the other right ascension, or the hour angle, so that the telescope may be directed, even in the daytime, to any star or other object whose right ascension and declination are known. The motion in right ascension is sometimes communicated by clockwork, so as to keep the object constantly in the field of the telescope. Called also an equatorial telescope. [1913 Webster]
" The term equatorial, or equatorial instrument, is sometimes applied to any astronomical instrument which has its principal axis of rotation parallel to the axis of the earth." [1913 Webster]

equatorial, adj. of or near the equator.

Idiom:
equatorial telescope a telescope attached to an axis perpendicular to the plane of the equator.

Derivative:
equatorially adv.

N  middle, midst, mediety, mean, medium, middle term, center &c, mid-course, mezzo termine, juste milieu, halfway house, nave, navel, omphalos, nucleus, nucleolus, equidistance, bisection, half distance, equator, diaphragm, midriff, intermediate, middle, medial, mesial, mean, mid, median, average, middlemost, midmost, mediate, intermediate, equidistant, central, mediterranean, equatorial, homocentric, in the middle, midway, halfway, midships, amidships, in medias res.

equatorial current, equatorial guinea, equatorial guinea monetary unit, north equatorial current, south equatorial current