from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A colorless, highly flammable gaseous element, the lightest of all gases and the most abundant element in the universe, used in the production of synthetic ammonia and methanol, in petroleum refining, in the hydrogenation of organic materials, as a reducing atmosphere, in oxyhydrogen torches, and in rocket fuels. Atomic number 1; atomic weight 1.00794; melting point -259.14°C; boiling point -252.8°C; density at 0°C 0.08987 gram per liter; valence 1. See Table at element.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. The lightest chemical element (symbol H) with an atomic number of 1 and atomic weight of 1.00794.
- n. Molecular hydrogen (H2), a colourless, odourless and flammable gas at room temperature.
- n. An atom of the element.
- n. A sample of the element.
from the GNU version of the Collaborative International Dictionary of English
- n. A gaseous element, colorless, tasteless, and odorless, the lightest known substance, being fourteen and a half times lighter than air (hence its use in filling balloons), and over eleven thousand times lighter than water. It is very abundant, being an ingredient of water and of many other substances, especially those of animal or vegetable origin. It may by produced in many ways, but is chiefly obtained by the action of acids (as sulphuric) on metals, as zinc, iron, etc. It is very inflammable, and is an ingredient of coal gas and water gas. It is standard of chemical equivalents or combining weights, and also of valence, being the typical monad. Symbol H. Atomic weight 1.
from The Century Dictionary and Cyclopedia
- n. Chemical symbol, H. One of the elementary substances, existing as a colorless, tasteless, and inodorous gas.
- n. H2S, a colorless inflammable gas having a sweetish taste and an exceedingly fetid smell resembling rotten eggs. It is extremely poisonous when inhaled. It has feeble acid properties, and its compounds with bases are called sulphids. It occurs in the emanations of volcanoes, and is evolved when animal or vegetable tissue containing sulphur decays. It also occurs in mineral springs, being liberated by the reduction of gypsum or other sulphates through the action of a microbe.
- n. Hydrogen compounds with strongly electronegative elements or radicals, easily exchanging hydrogen for strongly electropositive elements or radicals to form salts, are the same as acids: as hydrogen chlorid (hydrochloric acid), hydrogen sulphate (sulphuric acid), etc.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a nonmetallic univalent element that is normally a colorless and odorless highly flammable diatomic gas; the simplest and lightest and most abundant element in the universe
French hydrogène : Greek hudro-, hydro- + French -gène, -gen.(American Heritage® Dictionary of the English Language, Fourth Edition)
From French hydrogène, coined by Louis-Bernard Guyton de Morveau, from Ancient Greek ὕδωρ (hudōr, "water") + γεννάω (gennaō, "I bring forth"). (Wiktionary)