| EXHILARATINGLY | • exhilaratingly adv. In a way that exhilarates. • EXHILARATING adv. EXHILARATE, to make cheerful and excited. |
| EXOTHERMICALLY | • exothermically adv. In an exothermic manner. • EXOTHERMIC adv. of a chemical reaction, giving out heat, also EXOTHERMAL. |
| EXTRAVEHICULAR | • extravehicular adj. Relating to, on happening in, the space outside a vehicle, especially a spacecraft in space. • extra-vehicular adj. Alternative spelling of extravehicular. • EXTRAVEHICULAR adj. taking place outside a vehicle (as a spacecraft). |
| HYDROXYAPATITE | • hydroxyapatite n. A basic calcium phosphate mineral that is the principal inorganic constituent of bone and teeth. • HYDROXYAPATITE n. a complex phosphate of calcium that occurs as a mineral and is the chief structural element of vertebrate bone. |
| HYDROXYLATIONS | • hydroxylations n. Plural of hydroxylation. • HYDROXYLATION n. the act of hydroxylating. |
| HYPERCATALEXIS | • hypercatalexis n. (Poetry) The addition of one or two syllables to the last foot of a verse. • HYPERCATALEXIS n. the state of being hypercatalectic. |
| HYPEREXCITABLE | • hyperexcitable adj. Unusually or excessively excitable. • HYPEREXCITABLE adj. excessively excitable. |
| HYPERSEXUALITY | • hypersexuality n. The desire for sexual activity at levels high enough to be considered clinically significant. • HYPERSEXUALITY n. the state of being hypersexual. |
| LEXICOGRAPHIST | • lexicographist n. (Chiefly archaic) A student specialising in the discipline of lexicography; lexicographer. • LEXICOGRAPHIST n. one who makes dictionaries. |
| XANTHOCHROISMS | • XANTHOCHROISM n. a condition in which all skin pigments except yellow disappear. |
| XANTHOCHROMIAS | • XANTHOCHROMIA n. any yellowish discoloration, esp. of the cerebrospinal fluid. |
| XANTHOPTERINES | • XANTHOPTERINE n. a yellow pigment obtainable from the wings of yellow butterflies and the urine of mammals, also XANTHOPTERIN. |
| XEROPHTHALMIAS | • xerophthalmias n. Plural of xerophthalmia. • XEROPHTHALMIA n. extreme dryness of the conjunctive, thought to stem from a vitamin A deficiency, also XEROMA. |
| XEROPHYTICALLY | • xerophytically adv. As a xerophyte. • XEROPHYTIC adv. able to withstand drought. |
| XIPHIPLASTRALS | • XIPHIPLASTRAL n. a type of chelonian. |