Is there a word in which the concept and its complement is expressed, for example if I would like to express "the dichotomy of truth and falsehood" in one word. Obviously, the construction need not exist in English. I got this idea from the verb from 6 in Arabic, which is to express the reciprocal تقتاتل، تكاتب etc, i.e to correspond with each other, to kill one another.
There are many in Sanskrit सतासत् n. satAsat true and the false See Monier Williams Sanskrit Dictionary at http://www.spokensanskrit.org/index.php?mode=3&tran_input=satAsat&direct=se Other samAsas or joining words examples like
happiness + sorrow = happiness & sorrow सुख | दुक्ख = सुखदुक्ख
true+ false = true and false सत्य | असत्य = सत्यासत्य
strong +weak= strong & weak बल | अबल = बलाबल
Sounds like you're referring to words such as "length".
Is that what you mean, or are you looking for words that explicitly morphologically consists of a pair of antonyms for that?
If the latter is the case, then Mandarin Chinese. The concept of "the degree of which" is commonly formed by pairing up the pair of antonyms. For example:
dàxiǎo lit. "big small";
lěngnuǎn lit. "cold warm";
lěngrè lit. "cold hot";
chángduǎn lit. "long short";
shēnqiǎn lit. "deep shallow";
"Height (elevation)" 高低
gāodī lit. "high low";
"Height (bodily)" 高矮
gāo'ǎi lit. "tall short";
pàngshòu lit. "overweight slim";
duōshǎo or (literary) 多寡
duōguǎ, lit. "many few";
duìcuò lit. "right wrong" or (in the factual sense) 正误
zhèngwù lit. "correct mistaken";
"Position in an ordered sequence (e.g. a queue)" 先后
xiānhòu lit. "prior anterior".
Apart from these, besides lexically specific formations, an alternative generic formation also exists that uses 度
dù "degree" attached to the more semantically unmarked one, like English does with
magn- "big; great" +
Oh, and "the dichotomy of truth an falsehood" would really literally be
zhēnjiǎ "truthfulness", lit. "true false", or
zhēnwěi "authenticity" lit. "true fake".
xūshí "realness" lit. "phantom real".
More specifically, this formation probably expresses "(the quality of falling in) the semantic space spanned by the constituent morphemes", as Mandarin also has
xiōngdìjiěmèi "sibling(s)" lit. "elder-brother younger-brother elder-sister younger-sister",
xiōngdi "brother(s)" lit. "elder-brother younger-brother",
jiěmei "sister(s)" lit. "elder-sister younger-sister",
dì(di)mèi(mei) "younger member(s) of the sibling(s)" lit. "younger-brother younger-sister",
tiāndì "this whole world" lit. "sky earth",
qiánhòuzuǒyòu "all sides (of you)" lit. "front back left right",
dōngxīnánběi "all (geographic) directions" lit. "east south west north"/"east west south north".
If this is a thing, as the other answers imply, then German sprechen "speak", from *spreg- could be seen as composed of
*pr-, *per (whence pro, for),
*eks- (whence "ex"; reconstructed variously) either suffixed or prefixed,
and containing an s-mobile (thus compare *prey-, *preg, especially *prek- "to ask"), that by estimate might reflect *eks, in which case the coda would still need an explanation (how about co-, con-, see below!?)
Thus, the meaning would be similar to "back and forth", "pro and contra", Ger. "hin und her", "für und wieder" in the sense exchange.
PS: Also compare express.