I can look up the etymology for indubitably… but how did a word like this, which pretty much exactly parallels "undoubtedly," come into use? This might be an unanswerable question, but how did two words with such parallel meanings, the only nuance distinguishing them being that you sound more pretentious if you say "indubitably", come to coexist?
Learn English – Usage evolution of “indubitably”
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What's happened is that the verb to sanction has retained the original sense relating to endorsement/recognition by official decree.
But the noun sanctions (invariably pluralised, frequently imposed or applied) has come to mean measures taken by authority (often, multiple cooperating authorities) to discourage unsanctioned activities. By default, it's usually governments restricting trade in certain goods and services with some other nation, in order to put pressure on its government.
There is also the "positive" singular noun give (ones) sanction, but as that link shows, it's rapidly declined as the "negative" plural noun impose sanctions has gained currency.
Although superficially this looks odd, in practice there's unlikely to be any confusion because the verb / plural noun distinction is almost always made.
Having said all that, usage does change. Increasing numbers of younger speakers rarely hear the verb or singular noun form with positive associations, and they effectively "back-form" a new verb form they want to mean to impose sanctions. @Jay has identified a few such usages already in "print", and much as they make me cringe, doubtless there will be more in future.
You'll probably be disappointed, but the adverb does not have so many different meanings: words that express a general idea take (apparently) different meanings in different contexts.
Take for example long : it mean 'extended' and has a different meaning if you refer it to time or to space.
just expresses the general idea of
- exactly/ neither more nor less,
"It is impossible to say just what I mean!" (T.S. Eliot) or, more loosely,
- closely, and it may be referred to
space :
"...They had been standing just by the door..." (Thomas Hardy)
quantity:
- a little more/less than or
- not much more than (from which you get the impression it has changed meaning to only/ barely) :
"It is ridiculous to think you can spend your entire life with just one person" (The Observer), ( "Bob was just a dishwasher until he met George Lucas").
time:
- then, or
- a little earlier/ later than..
"Alice was just asking Noel... when she heard..." (E. Nesbit), "I think I have just swallowed..." (I. Murdoch), "Tell his excellency I am just a coming" (D. Defoe)
It is as simple as that!
(the examples are from SOED)
You've indicated three general meanings that might apply to some, but not all, of the more specific meanings I listed in the initial question (how to account for "possibly," "quite or very," and "directly"?). Also, I find it interesting that two of the general ideas you've indicated contradict each other: "neither more nor less" and "a little more or less." That's worth a question in and of itself. So, yeah, a little disappointed. – Rusty Tuba
I have indicated just one meaning, if you reflect just a bit, you'll see no contradiction between exactly (neither more nor less, quite,.. etc) and almost exactly (a little more/less... etc), it is only approximation, which is a natural feature of language. Bearing this in mind, you'll be able to clarify all other optical illusions. I didn't list all possibilities because it is not a closed list.
Best Answer
There is actually a subtle distinction between the two words: undoubtedly means "not doubted" whereas indubitably means "beyond doubt" i.e. that which cannot be doubted as opposed that which is not doubted.
This answer serves to illustrate, in part, the more general question you've raised. There is a phenomenal plethora of synonyms in English (Hungarian takes the trophy, though) and it is largely due to the language's mongrel heritage, in turn caused by successive waves of conquerors and invaders putting down roots in the land. We have roots in a number of Celtic, West Germanic and Romance languages, and so an extraordinary arsenal of vocabulary has been available to us. As a result, we have been able to use these synonyms to inject the language with subtler shades of meaning than would be afforded by a single linguistic root. Why this quality is more apparent in English than in some other languages is not entirely clear (we're certainly not unique in our mongrel heritage) and the debate continues among linguists today.
Regarding "pretentious" synonyms, I believe this has its origins in the days when French was the language of the court and Latin that of the clergy, while common old guttural, germanic, dialectic English was the language of the peasantry. The association of Romance languages (and therefore longer words of latin-style inflection) with the higher classes of society has stuck with us, and the hangover of this can be observed, for example, in the extensive use of French in "legalese."