Hypochlorous acid Hypochlorous acid is a weak acid with the chemical formula HydrogenOxygenChlorine. It forms when chlorine dissolves in water. It cannot be isolated in pure form due to rapid equilibration with its precursor. HOCl is used as a Bleach, an oxidation, a deodorant, and a disinfectant.
	Hypocycloid In geometry, a hypocycloid is a special plane curve generated by the trace of a fixed point on a small circle that rolls within a larger circle. It is comparable to the cycloid but instead of the circle rolling along a line, it rolls within a circle. If the smaller circle has radius r, and the larger circle has radius R = kr, then the
	Hypodermic needle A hypodermic needle is a hollow needle commonly used with a syringe to inject substances into the body. They may also be used to take liquid samples from the body, for example taking blood from a vein in venipuncture. A hypodermic needle is used when the substance would not be reliably absorbed by the digestive system, when the substance in question would harm the liver if made to pass through the digestive system, or if the substance needs to be instantly delivered into the body.
	Hypopachus Hypopachus is a genus of Microhylidae frogs. Species * Hypopachus barberi Schmidt, 1939. * Hypopachus variolosus.
	Hypophosphorous acid Hypophosphorous acid is a phosphorus oxoacid and a powerful Reduction. Inorganic chemists refer to the free acid by this name although its official IUPAC nomenclature of inorganic chemistry is phosphinic acid. It is a colorless low-melting compound, which is soluble in water, dioxane, and alcohols.
	Hypothalamus The hypothalamus is a region of the mammalian brain located below the thalamus, forming the major portion of the ventral region of the diencephalon and functioning to regulate certain metabolic processes and other autonomic activities. The hypothalamus links the nervous system to the endocrine system via the pituitary gland, also known as the "master gland," by synthesizing and secreting hormone, often called releasing hormones, as needed that control the secretion of hormones
	Hypoxidaceae Hypoxidaceae is the botanical name of a family of flowering plants. Such a family has not been recognized by many taxonomists. The APG II system, of 2003, does recognize this family and places it in the order Asparagales, in the clade monocots. The family consist of probably over half-a-dozen genera totalling some one hundred to two hundred species.
	Hypsiglena Hypsiglena is a genus of small, rear-fanged, colubrid snakes commonly referred to as night snakes. The genus consists of two distinct species, many subspecies may be considered synonymous depending on the source.
	Hypsiglena torquata Hypsiglena torquata is a species of rear-fanged, colubrid snake known as the night snake. They are found through the south and western United States, as well as Mexico. The number of subspecies varies depending on the source, but it is generally accepted that there are 17.
	Hypsography Hypsography refers to the distribution of elevation on the surface of the Earth, and is sometimes applied to other rocky planets such as Mars or Venus. The term originates from the Greek language word "Hypso" meaning height. Most often it is used only in reference to elevation of land but a complete description of Earth's solid surface requires a description of the seafloor as well.
	Hyrax A hyrax is any of four species of fairly small, thickset, herbivorous mammals in the order Hyracoidea. They live in Africa and the Middle East. Despite the unexceptional appearance of modern hyraxes, the order has a remarkable prehistoric lineage and hyraxes may be the closest living relatives of the elephant.
	Hyssop Hyssopus can also refer to a genus of Hymenopteran insects of the family Eulophidae Hyssop is a genus of about 10-12 species of herbaceous or subshrub plants in the family Lamiaceae, native from the Mediterranean east to central Asia.
	Hysteresis Hysteresis is a property of systems that do not instantly follow the forces applied to them, but react slowly, or do not return completely to their original state: that is, systems whose states depend on their immediate history. For instance, if you push on a piece of putty it will assume a new shape, and when you remove your hand it will not return to its original shape, or at least not immediately and not entirely.
	Hysteroscopy Hysteroscopy is the inspection of the uterus by endoscopy. It allows for the diagnosis of intrauterine pathology and serves as a method for surgical intervention.
	Hystricomorpha The term Hystricomorpha has had many definitions throughout its history. In the broadest sense it refers to any rodent with a hystricomorphous zygomasseteric system. This includes the Hystricognathi, Ctenodactylidae, Anomaluridae, and Pedetidae. Molecular and morphological results suggest that the inclusion of the Anomaluridae and Pedetidae in Hystricomorpha may be suspect.