a. [f. L. ad to + umbra shade + -AL 1; with reference to adumbrāre, ADUMBRATE v. 4.]
1. Of overshadowing nature; shady.
1845. Blackw. Mag., LVII. 246. This circular adumbral and pluvial roofing had to be adapted to the female head.
2. Zool. A shortened equivalent of ADUMBRELLAR.
1881. E. R. Lankester, in Jrnl. Microsc. Sc., Jan., 124. The cells of the adumbral walls are like those of the ring-canals.