| CHTHONIAN | • chthonian adj. Pertaining to the underworld; being beneath the earth. • chthonian n. A dweller in the mythical underworld. • CHTHONIAN adj. pertaining to the earth or the underworld, also CHTHONIC. |
| DIPHTHONG | • diphthong n. (Phonetics) A complex vowel sound that begins with the sound of one vowel and ends with the sound of… • diphthong n. (Rare) A vowel digraph or ligature. • DIPHTHONG n. a union of two vowels pronounced in one syllable. |
| ICHTHYOID | • ichthyoid adj. Characteristic of fish. • ichthyoid n. Any fish, or other vertebrate having the form of a fish. • ICHTHYOID adj. fishlike, also ICHTHYOIDAL. |
| ICHTHYSES | • ichthyses n. Plural of ichthys. • ICHTHYS n. (Greek) an emblematic fish symbolizing Christ, believed to have mystical qualities. |
| NAPHTHENE | • naphthene n. (Organic chemistry) Any cycloalkane (or alkyl derivative). • NAPHTHENE n. a peculiar hydrocarbon occurring as an ingredient of Caucasian petroleum. |
| NAPHTHOLS | • naphthols n. Plural of naphthol. • NAPHTHOL n. any one of a series of hydroxyl derivatives of naphthalene, analogous to phenol, also NAPHTOL. |
| NAPHTHOUS | • NAPHTHOUS adj. containing naphtha. |
| NAPHTHYLS | • naphthyls n. Plural of naphthyl. • NAPHTHYL n. a radical derived from naphthalene. |
| NIGHTHAWK | • nighthawk n. (UK, regional) A nightjar, especially Caprimulgus europaeus (Eurasian nightjar). • nighthawk n. (US) A New World nightjar of the genus Chordeiles, especially Chordeiles minor. • nighthawk n. A person whose preference or custom is to remain awake and active during the night and the early morning hours. |
| PHTHALATE | • phthalate n. (Organic chemistry) Any salt or ester of a phthalic acid. • PHTHALATE n. a salt of phthalic acid. |
| PHTHALEIN | • phthalein n. (Organic chemistry) any of a range of lactones formed by the reaction of phenols with phthalic anhydride. • PHTHALEIN n. any one of a very important class of dye-yielding materials formed by the union of phenols with phthalic anhydride. |
| PHTHALINS | • phthalins n. Plural of phthalin. • PHTHALIN n. a colourless crystalline compound obtained by reducing a phthalein. |
| PHTHISICS | • phthisics n. Plural of phthisic. • PHTHISIC n. a disease of the lungs, also PHTHISIS. |