In the context of chemistry and materials, organic refers to a materials based on carbon (a chemical element abbreviated as C). Additional elements that are commonly found in organic materials are hydrogen (H), nitrogen (N), oxygen (O), phosphorus (P) and sulfur (S). An unrelated and confusing definition of organic is used most often in reference to "natural" foods. For example, a simple definition of "organic produce" is fruits or vegetables that have been raised without the use of pesticides or herbicides. Of course, many pesticides and herbicides are actually themselves organic (using either or both definitions of "organic")! Materials that are not organic are usually referred to as inorganic. Additional Info: Organic chemicals are not necessarily harmful ortoxic. Much or the human body consists of organic chemicals such as proteins, DNA, lipids and cell membranes. The food you eat, trees, grass, and every other living object contains organic compounds. The term "carbon-based life forms" is redundant (at least on this planet). However, this does not necessarily mean all organic chemicals are good for you. For example, hydrogen cyanide (HCN) is a deadly toxin, benzene (C6H6) is a carcinogen and thalidomide is a potent teratogen(but also a useful medicine!). When it comes to considering the toxicity of any material, remember that the dose makes the poison. Some chemicals (organic or not) present no or minimal hazard even at very high concentrations, while others can be deadly in minute amounts. Some organic compounds are highly reactive and are incompatible with other chemicals such as strong oxidizing agents. Be sure to read your MSDS! MSDS Relevance: Don't simply classify compounds as "organic" when identifying hazards. There are broad classes of organic compounds (such as hydrocarbons etc.) that you may be able to do this with, but remember that there are over 10,000,000 known organic compounds. These have a wide variety of health effects and hazards, many of which are not fully known. Therefore, always read the MSDS before working with a new material to orient yourself to the hazards specific to the chemicals with which you are working. If the hazard is not known, utilize what is termed "universal precautions"; i.e. treat the material as if it were extremely hazardous or highly toxic. See also: Cyanide, Ether, Halogen, Hydrocarbon, Nitrile, Solvent, Volatile Organic Compounds (VOC's)