v. [f. TRANS- + ILLUMINATE v.] trans. To cause light to pass through; spec. in Med. to throw a strong light through (an organ or part) to discover the presence or cause of disease. So Transillumination, the action or process of transilluminating.
1890. Lancet, 1 March, 480/2. It [a tooth] was translucent by electric transillumination, showing that the pulp was living. Ibid. (1900), 25 Aug., 617/1. If in a darkened room the electric lamp used for transilluminating the frontal sinus was placed against the thyroid cartilage. Ibid. (1901), 11 May, 1328/2. Transillumination is often used to find out if the antrum is diseased.
1912. Keith, Human Body, i. 20. It may have occurred, however, to the onlooker that, since we can trans-illuminate the human body [i.e., with Röntgen-rays], it is no longer necessary to dissect it.
