(n.) The act of refracting, or the state of being refracted.
(n.) The change in the direction of ray of light, heat, or
the like, when it enters obliquely a medium of a different density from
that through which it has previously moved.
(n.) The change in the direction of a ray of light, and,
consequently, in the apparent position of a heavenly body from which it
emanates, arising from its passage through the earth's atmosphere; --
hence distinguished as atmospheric refraction, or astronomical
refraction.
(n.) The correction which is to be deducted from the
apparent altitude of a heavenly body on account of atmospheric
refraction, in order to obtain the true altitude.
