(1):
(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.
(2):
(a.) Negligent; heedless; indolent; listless.
(3):
(a.) Lying on the back, or with the face upward; - opposed to prone.
(4):
(a.) Leaning backward, or inclining with exposure to the sun; sloping; inclined.