Solidus (Latin) is the name of a Roman coin during the Roman Empire. Soldiers were paid with Solidus therefore they were Solidarius=Soldier. Solidare in Latin is to pay. The word soldier is an Old French word, derivation of Solidarius.

In chemistry, materials science, and physics, the solidus is a line on a phase diagram below which a given substance is stable in the solid phase. Most commonly, this line represents a transition temperature. The solidus may be a straight line, or it may be curved, depending upon the substance. The solidus is most often applied to binary systems such as solid solutions, including metal alloys. Chemistry (in Greek: χημεία) is the science of matter and its interactions with energy and itself (see physics, biology). ... The Materials Science Tetrahedron Materials science is a multidisciplinary field focusing on functional solids, whether the function served is structural, electronic, thermal, chemical, magnetic, optical, or some combination of these. ... The willingness to question previously held truths and search for new answers resulted in a period of major scientific advancements, now known as the Scientific Revolution. ... A phase diagram or phase space is a useful construct used in mathematics and physics to demonstrate and visualise the changes in a given system. ... A solid is a state of matter, characterized by a definite volume and a definite shape (i. ... Temperature is the physical property of a system which underlies the common notions of hot and cold; the material with the higher temperature is said to be hotter. ... Binary system may refer to one of the following. ... Hot metal work from a blacksmith In chemistry, a metal (Greek: Metallon) is an element that readily forms ions (cations) and has metallic bonds, and metals are sometimes described as a lattice of positive ions (cations) in a cloud of electrons. ... An alloy is a combination, either in solution or compound, of two or more elements, at least one of which is a metal, and where the resultant material has metallic properties. ...

The solidus may be contrasted to the liquidus. The solidus and liquidus do not necessarily align or overlap; if a gap exists between the solidus and liquidus, then within that gap, the substance is not stable as either a solid or a liquid. In chemistry, materials science, and physics, the liquidus is a line on a phase diagram above which a given substance is stable in the liquid phase. ... A liquid will assume the shape of its container. ...