a. [ad. Gr. κερατοειδής horn-like: see prec. and -OID.]
1. Math. Resembling a horn in shape. Keratoid cusp: a cusp at which the two branches of the curve lie on opposite sides of the common tangent; a cusp of the first species.
1873. Salmon, Higher Plane Curves, 46. These two kinds of cusps have been called keratoid and ramphoid from a fancied resemblance to the forms of a horn and a beak.
1875. Todhunter, Diff. Calc. (ed. 7), xxii. § 301. Cusps of the first species have been called ‘keratoid cusps.’
2. Resembling horn in substance.
1885–8. Fagge & Pye-Smith, Princ. Med. (ed. 2), I. 117. The analogy of keratoid carcinoma … suggests that they may be in great part made up of pre-existing tissue elements.
