a. - Lying on the back, or with the face upward; -- opposed to prone.
a. - Leaning backward, or inclining with exposure to the sun; sloping; inclined.
a. - Negligent; heedless; indolent; listless.
n. - A verbal noun; or (according to C.F.Becker), a case of the infinitive mood ending in -um and -u, that in -um being sometimes called the former supine, and that in -u the latter supine.