The term 'plastic' means, generally, 'easily moulded or shaped'.
Online dictionaries tend to show only a few of the very many variants and meanings of the term 'plastic'.
I have tried here to compile a list of the more frequent uses of the term 'plastic' across the internet.
That list may be found at the foot of this article.
The Plasticity of the Word 'Plastic'.
Words that refer to themselves are called autological words. They can generate some interesting paradoxes. The word plastic can be pronounced as plass-tick, plarz-tick, plause-tick etc., and so it describes its own pronunciation, and that of every other word. I suggest, then, that the term 'plastic' is an absological word, meaning that it is a term that may be applied, not only to itself, but to every other word in the language. Other absological words would include 'spelled' and 'pronounced'. All of language is 'plastic' in the sense of being easily moulded. Actors mould their dialects, pedants mould their grammar. The people, in spite of the pedants, mould the national language into a communal tool.
Words themselves are plastic, they are moulded and shaped over the course of the years by their users. One vowel-sound slides un-noticed into another, displacing it. In turn another vowel gets displaced. This vowel shift phenomenon was first named by Otto Jespersen, a founder of the International Phonetic Association. A sound shift in the German language was described by Jacob Grimm, of Grimm's Fairy Tales fame. His finding were adopted into linguistics as Grimm's law.
The Invention of Plastics.
In physics the term 'plastic' applies to the permanent deformation of a shape without fracture, as when a piece of metal is bent. In chemistry and engineering, a substance is called a plastic if at some stage in its production or use it can be moulded or shaped. The two major classes of plastic are thermoplastics and thermosetting plastics. In simple terms, a thermoplastic becomes deformable when heated, a thermosetting plastic loses its ability to be deformed when heated.
Nitrate, the first plastic, invented in 1889 is a class of explosive. The difference between an explosive and a combustible is the burn rate, or flame front advance rate. A conflagration is an uncontrolled burning. A deflagration is a 'burning down'. Nitrate film was used on movie film stock up until 1950s. it was the cause of some horrific fires in theatres. Even film archivists need to be aware of the damage that nitrate film stock can do. Of course, no mere chemical process can outdo a nuclear scale deflagration.
For the student of the chemistry of plastics, recommended further reading:
The Story of Polyethylene by Robert H Holley
Plastic - some definitions.
Plastic - from words meaning a mould, to mould. (UK mould : US mold)
from Latin plasticus, Greek plastikos, plastos, plassein.
Suffixes: -plastic, -plasty
Variants: plastic, plasticity, plasticise
Neuroplasty: - plastic surgery to repair a nerve.
Plastic surgery: - surgical procedures to correct or restore the form and/or function of (usu. human) body parts.
A material or substance that, during or after manufacture, is readily moulded.
Easily shaped, formed, moulded - like putty or play-clay.
A quality of being easily shaped, formed or moulded.
A type of force that causes a thing to take on a shape
Meanings In the Arts and Sciences:
Chemistry: Compounds produced by polymerization, capable of being moulded, extruded, or drawn into filaments.
Psychology: Easily influenced, impressionable.
Physics: Capable of undergoing continuous deformation without rupture or relaxation.
Biology: Gene plasticity, or phenotype plasticity, refers to the property whereby genes do not express their instructions in a rigid, mechanistic way, but rather express guidelines. Note: this is my simplified wording. For a fuller description of this area of study see, e.g. Genome Plasticity.
Medicine: Capable of building or shaping tissue.
Cognitive Science 1: Neuroplasticity, synaptic plasticity - In studies of the brain, plasticity refers to the variability of neural growth other than through gene expression. See e.g. Neural Plasticity And the Self-Repairing Brain; Brain Plasticity and Behaviour.
Cognitive Science 2: In psychology, plasticity refers to the suggestibility of subjects.
Art: a type of paint in which the pigment consists of finely divided plastic particles. See e.g. Acrylic paint.
Derogatory: Artificial, superficial, cheap.
Informal: A credit or debit card and similar means for making payments without using cash or written instrument.