| HELIOCHROMY | • heliochromy n. (Dated) The art of producing colour photographs. • HELIOCHROMY n. photography in natural colours. |
| HETEROPHONY | • heterophony n. (Music) The simultaneous performance by a number of singers or musicians of two or more versions of the same melody. • HETEROPHONY n. an independent variation on a single melody by two or more voices. |
| HOBBYHORSED | • HOBBYHORSE v. of a vessel, to pitch violently. |
| HOBBYHORSES | • hobbyhorses n. Plural of hobbyhorse. • hobby-horses n. Plural of hobby-horse. • hobby␣horses n. Plural of hobby horse. |
| HOMEOMORPHY | • homeomorphy n. (Biology) The evolution of similar external forms from very distant ancestors. • homeomorphy n. (Mathematics) The formation of a new graph by inserting new nodes along existing edges. • HOMEOMORPHY n. the state of being homeomorphic, also HOMOMORPHY. |
| HOMEOTHERMY | • homeothermy n. The state or condition of being homeothermic. • HOMEOTHERMY n. the maintenance of a constant body temperature, also HOMEOTHERMISM, HOMOIOTHERMY, HOMOTHERMY. |
| HYDROCHORES | • hydrochores n. Plural of hydrochore. • HYDROCHORE n. a plant disseminated by water. |
| HYDROPHONES | • hydrophones n. Plural of hydrophone. • HYDROPHONE n. an apparatus for listening to sounds conveyed by water. |
| HYGROPHOBES | • HYGROPHOBE n. a plant growing best where moisture is scanty. |
| HYMENOPHORE | • hymenophore n. (Mycology) The part of a fungus fruiting body which produces spore-bearing cells. • HYMENOPHORE n. the fruiting body of some basidiomycetous fungi. |
| HYPOSTROPHE | • hypostrophe n. (Medicine) The act of a patient turning himself or herself. • hypostrophe n. (Medicine) A relapse, or return of a disease. • hypostrophe n. (Rhetoric) The use of insertion or parenthesis. |
| HYPSOCHROME | • hypsochrome adj. Hypsochromic. • HYPSOCHROME n. a shift to a shorter wavelength in the absorption spectrum of a compound. |
| ORTHOPHYRES | • ORTHOPHYRE n. a fine-grained syenitic rock with orthoclase crystals. |
| PHYTOCHROME | • phytochrome n. (Biochemistry) Any of a class of pigments that control most photomorphogenic responses in higher plants. • PHYTOCHROME n. a plant pigment which absorbs red or infrared rays and acts as an enzyme controlling growth. |
| RHYNCHOCOEL | • rhynchocoel n. A nemertean worm of the former phylum Rhynchocoela. • rhynchocoel n. A tubular cavity, in such worms and other organisms, enclosing a proboscis. • RHYNCHOCOEL n. the cavity in which the proboscis of a nemertine lies. |