why does 'flammable' and 'inflammable' mean the exact same thing?

Answer 1

Blame it on Latin and its tricky prefixes. In the beginning, there was "inflammable," a perfectly nice English word based on the Latin "inflammare," meaning "to kindle," from "in" (in) plus "flamma" (flame). "Inflammable" became standard English in the 16th century. So far, so good.

Comes the 19th century, and some well-meaning soul dreamt up the word "flammable," basing it on a slightly different Latin word, "flammare," meaning "to set on fire." There was nothing terribly wrong with "flammable," but it never really caught on. After all, we already had "inflammable," so "flammable" pretty much died out in the 1800's.

"But wait," you say, "I saw 'flammable' just the other day." Indeed you did. "Flammable" came back, one of the few successful instances of social engineering of language.

The Latin prefix "in," while it sometimes means just "in" (as in "inflammable"), more often turns up in English words meaning "not" (as in "invisible" -- "not visible"). After World War Two, safety officials on both sides of the Atlantic decided that folks were too likely to see "inflammable" and decide that the word meant "fireproof," so various agencies set about encouraging the revival of "flammable" as a substitute. The campaign seems to have worked, and "inflammable" has all but disappeared.

That left what to call something that was not likely to burst into flames, but here the process of linguistic renovation was easier. "Non-flammable" is a nice, comforting word, and besides, it's far easier on the tongue than its now thankfully obsolete precursor, "non-inflammable."

The Oxford English Dictionary adds this usage note: Historically, flammable and inflammable mean the same thing. However, the presence of the prefix in- has misled many people into assuming that inflammable means "not flammable" or "noncombustible." The prefix -in in inflammable is not, however, the Latin negative prefix -in, which is related to the English -un and appears in such words as indecent and inglorious. Rather, this -in is an intensive prefix derived from the Latin preposition in. This prefix also appears in the word enflame. But many people are not aware of this derivation, and for clarity's sake it is advisable to use only flammable to give warnings.

Answer 2

Flammability or Inflammability is the ease with which a substance will ignite, causing fire or combustion. Materials that will ignite at temperatures commonly encountered are considered flammable, with various specific definitions giving a temperature requirement. The flash point is the important characteristic. A volatile substance may have sufficient vapor pressure to form flammable (or even explosive) mixtures with air in temperatures as low as –10 °C, so that ignition can occur even without direct contact. Flash points below 100 °F (37.8 °C) are regulated in the United States by OSHA as potential workplace hazards. Examples of flammable liquids are gasoline, ethanol, and acetone. Diesel fuel is in one of the less heavily regulated flammability categories, and biodiesel is considered nonflammable or noninflammable with a flash point usually over 300 °F (150 °C) even though biodiesel will combust inside a diesel engine.

The word flammable is of relatively recent origin but has in many contexts, especially safety, taken the place of the word inflammable, an older term with the same meaning. Some people, especially young children and non-native English speakers, find inflammable confusing, thinking that the Latin prefix in- (here an intensifier) always means "not" [1]. The "in-" comes from the latin preposition "in". Because many people assumed that the "in-" meant not, the corruption "flammable" has become more prevalent. To avoid this confusion, in some countries such as the United States, trucks carrying gasoline and other flammable substances are marked "flammable". In other countries, such as India, lorries carrying petrol and other inflammable substances are marked "highly inflammable".[2] The Chicago Manual of Style suggests using "flammable" for clarity.[3] The Elements of Style ("Strunk and White") says

Flammable. An oddity, chiefly useful in saving lives. The common word meaning "combustible" is inflammable. But some people are thrown off by the in- and think inflammable means "not combustible." For this reason, trucks carrying gasoline or explosives are now marked FLAMMABLE. Unless you are operating such a truck and hence are concerned with the safety of children and illiterates, use inflammable

Answer 3

Here's something I copied from the Encarta online Dictionary. I think it explains all.
flammable or inflammable? Although inflammable looks like the opposite of flammable, the two words actually have the same meaning, both describing something that is easily set on fire. The in- prefix of inflammable means "into," rather than "not," and the adjective is ultimately derived from the same Latin word as the verb inflame. In view of the potentially disastrous consequences of such misinterpretation, flammable has become the word of choice, especially in the labeling of commercial and industrial products. The word most frequently used to convey the opposite meaning is nonflammable."

Answer 4

Dr. Nick Riviera (The Simpsons) pondered that same question years ago after a firecracker explodes a can marked INFLAMMABLE. "Inflammable means flammable?! Boy, what a country."

Answer 5

<>It is an oddity of the English language. For many years, inflammable was used to describe the combustibility of factor. In recent years, liguists have begun to realize that the "in-" in "inflammable" is redundant and unnecessary, and have reduced the word to its synonym, "flammable."

Answer 6

Wood is flammable, propane is inflammable, clears your confusion?

Answer 7

Inflammable means unable to burn. Flammable means that it will burn. They are not the same thing.

Answer 8

? I've never even heard the word "inflammable". I don't even think that that's a word...