請問flammable和inflammable詞義相同，有什麼原因嗎？

12-28

這問題我還真能答，去年在班級群里「裝過逼」
無知的我「裝逼一時爽」，居然狂妄地稱「in」是inflammable里的前綴！

於是，好奇的我查了一下，又繼續開始「裝逼」了 ?

不過這些裝逼內容都是從網上查到的啦
論詞源果然還是得強推韋氏詞典
所以我剛剛又查了一下，它的大致內容基本我在前面的對話中都有提到（畢竟其實當時裝逼就是靠著它

希望能幫到你。

"Flammable" and "inflammable" have exactly the same meaning. (Many other answers have explained it.)

The opposite of "flammable" is "non-flammable", "fireproof", and "fire retardant".

There are some other pairs of words like "flammable" and "inflammable". They seem like opposites, but they are very closely related (not necessarily the same). For example:

"impassive" and "passive"
"irradiated" and "radiated"
"unravel" and "ravel"
"inhabitable" and "habitable"
"invaluable" and "valuable" (「Invaluable」 is more valuable than 「valuable」, like "無價的" is more valuable than "貴的". Thanks @Liege Chine and @王贇 Maigo for pointing it out. )

I hope this is helpful.

**************************************

栗子的知乎答案索引：栗子樹

栗子的微信公眾號：E-Speller 或者 栗子英文 （只有精彩的原創）

**************************************

inflammable 的源頭是拉丁語 inflammare（&< in+flmma）。這裡的拉丁語前綴 in- 是英語的「in，on」的意思，inflammare 的意思就是把……放到火上，放火的意思。

flammable 的出現就是為了解決 inflammable 容易造成歧義的問題。

in-有兩個來源，兩個意思，一個表示否定（來自拉丁語和英語固有的un-同源），一個表示和英語的介詞in差不多的意思（來源是拉丁語相近的介詞in），也可以表示使進入某一狀態（這個詞綴經過法語後變成了en-，比如enable）。這裡是後者。

摘自風格的要素，The Element of Style。
By William Strunk

《Oxford Dictionary of English》：

《The Merriam-Webster Dictionary》：

Oxford Dictionary of English和The Merriam-Webster Dictionary是兩本非常好用的母語詞典，很多辭彙上的問題都能在這兩本詞典里找到答案，這裡分享給你（鏈接：http://pan.baidu.com/s/1geWd1TL 密碼：749j 推薦手機上使用歐路，電腦上用GoldenDict），希望對你有所幫助。

其他詞典上的解釋：

《英語常用詞疑難用法手冊》：

儘管後者有前綴in-，但這個in-沒有否定的意思。兩者都是「易燃的」（科研用語似乎多用flammable，工業用語似乎多用inflammable，但是美國一些換液化氣罐的地點在告示牌上常用flammable而不用inflammable）。只有inflammable可以轉義為「易發火的、易怒的」、「衝突一觸即發的」。【例如】There was an inflammable confrontation between the two countries. 兩國彼此對峙，衝突一觸即發。in-沒有否定意義的情況，參見inhabitable與habitable條。

《The American Heritage Dictionary of the English Language 》：

Inflammable means "combustible," and has the same meaning as the word flammable. How is this possible? The prefix in- here is not the Latin negative prefix in- (which is related to the English un- and appears in words such as indecent and inglorious) but is derived from the Latin preposition in, "in." This prefix is the source of the en- in words like enflame. However, some people mistakenly think that inflammable means "not flammable." Therefore, for clarity"s sake, it is safest to avoid inflammable altogether and use flammable instead.

《Garner"s Modern American Usage》：

flammable; inflammable

The first is now accepted as standard in AmE and BrE alike. Though examples of its use date back to 1813, in recent years it has become widespread as a substitute for inflammable, in which some people mistook the prefix in- to be negative rather than intensive—e.g.: 「[T]heir fire-place is mounted in a black box built out of an inflammable [read a nonflammable or a noninflammable] material made of pressed paper.」 Michael Cannell, 「A 180-Degrees View of a Hotbed of Housing Design,」 N. Y. Times, 4 Jan. 2007, at F7. Traditionally, the forms were inflammable and noninflammable; today they are flammable and nonflammable. By the mid-20th century, purists had lost the fight to retain the older forms. See NEGATIVES (A).

Even staunch descriptivists endorsed the prescriptive shift from inflammable to flammable—e.g.: 「A word is bad if it is ambiguous to such a degree that it leads to misunderstanding. For me, the perfect example of such a word is inflammable, if it is applied to substances. As most dictionaries now recognize, inflammable can be confused with non-combustible, and so lead to accidents.」 Archibald A. Hill, 「Bad Words, Good Words, Misused Words,」 in Studies in English Linguistics for Randolph Quirk 250, 252 (1983). Cf. inflammatory.

《Pocket Fowler"s Modern English Usage》：

flammable
meaning 『easily set on fire』, was revived in modern use (in BrE by the British Standards Institution) and used together with the noun flammability in place of inflammable and inflammability (which have the same meaning) in order to avoid the possibility that the in- forms might suggest a negative meaning 『not easily set on fire』. The negative forms now recommended are non-flammable and non-flammability .

區別之於：怒火與怒火中燒，in就是強調＂中＂了。

愚蠢的英語，可以燒的，易燃燒的，都一個寫法，不混淆才怪。

in-有兩個，一個表示否定，不能單獨使用；另一個表示介詞in，（in + abl. 代表in，in + acc. 代表into，不過這是介詞……）
這裡的in應該是表示進入（代表in這個介詞），為了加強語氣……re-, con-等詞綴有時也有加強語氣的意思……

flammable 可燃的 flam 假話

inflammable 易燃的 inflam 燃燒的

故 inflammable 才是正統（看來「inflam」這六個字母應該是一體的，而不是「in-flam」的兩個詞的組合）

只不過由於 "in" 的存在讓人會誤以為它是「不可燃的」的意思

所以再造一個去掉 in 的新詞以減少誤解

Inflammable比flammable更容易著火。