‖ ruga Bot., Zool., etc.
(ˈruːgə)
Pl. rugæ (ˈruːdʒiː).
[L. rūga.]
A wrinkle, fold, or ridge.
| 1775 J. Jenkinson tr. Linnæus' Brit. Pl. Gloss. 256 Rugose, full of rugæ or wrinkles. 1797 Encycl. Brit. (ed. 3) II. 387/2 The vermicularis, with faint annular rugæ. 1821 W. P. C. Barton Flora N. Amer. I. 125 An oblong or barrel-shaped bulb, marked by circular lines or rugæ. 1879 St. George's Hosp. Rep. IX. 435 Its mucous membrane was drawn up into thick dark-brown rugæ. 1913 Cunningham's Text-bk. Anat. (ed. 4) 1298 When this muscular layer is contracted, the scrotum becomes smaller..and the skin is thrown into folds or wrinkles called rugæ. 1962 Gray's Anat. (ed. 33) 1514 The loose texture of the mucous layer allows the mucous coat to be thrown into folds or rugae when the bladder is empty. 1963 J. Osborne Dental Mech. (ed. 5) ii. 40 The rugae may be accentuated with blue inlay wax. 1969 Gloss. Terms Dentistry (B.S.I.) 107 Rugae, the irregular ridges of the mucous membrane covering the anterior part of the hard palate. |
Hence ˈrugal a.
| 1936 Kantner & West Phonetics (ed. 3) i. iii. 48 Attention should be drawn to the alveolar or rugal ridge which is the raised line of flesh found at the point where the teeth emerge from the gums. |