I
In biology, a conspicuous mass of mycelium and fruiting structures produced by various fungi (division Mycota; see fungus ).
Molds of the genera Aspergillus , Penicillium , and Rhizopus are associated with food spoilage and plant diseases, but some have beneficial uses, as in the manufacture of penicillin ) and certain cheeses. Neurospora , or orange bread mold, has been invaluable in the study of biochemical genetics. Water molds live in fresh or brackish water or wet soils, absorbing dead or decaying organic matter. See also slime mold .
Mold on surface of jelly
(Left) Ingmar Holmasen, (right) Stephen Collins
II
In manufacturing, a cavity or surface in which a fluid or plastic substance is shaped into a desired finished product.
A molten substance, such as metal or plastic, is poured or forced into a mold and allowed to harden. Molds are made of various materials, depending on the application; sand is frequently used for metal casting , hardened steel for molds for plastic materials, and plaster for various purposes. See also ingot , patternmaking , tool and die making .