"in-" can mean "not", for example, "inept", or "in", for example, "intoxicant".

Are there some general principles that will help us know when "in-" means which: "not" or "in"?

  • My strong guess is no. If the root is latin or English, it can be non-, in-, im-, ir-, dis- and un-. If greek: a-/an-. Lastly we have anti- – mplungjan Oct 21 '13 at 5:55
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    Perhaps the more difficult thing for people who did not grow up with English is to determine whether to use in.. or un.. as prefixes meaning 'not'. Germans especially seem to have difficulty with these. I had a colleague who would refer to things being 'unpossible' and to 'inofficial sources'. There is really no solution other than to learn them from experience. though you will always stand a 50-50 chance of getting the right one! – WS2 Oct 21 '13 at 7:44

There are two prefixes in- in Latin.

  1. In- meaning "not", related to the large family of nasal negations in the Indo-European languages, such as Latin non/ne/num/negatio, English un/not/never/no/negation(from Latin)/etc. I would say the English prefix un- most directly corresponds with Latin in-.

  2. In- meaning "in", from the Latin preposition in meaning "in(to)".

They are indistinguishable in form, so I'm afraid you will have to learn which prefix is used for each word separately. I don't believe there is much of a rule, not even in Latin. Some words can even lead to confusion among native speakers: inflammable means the same as flammable, so it is prefix number 2 meaning "in(to)". The negative word has to be unflammable (rarely used), but many people will confuse the two.


I don't think there is a general trend which you could detect in English.

My understanding of Latin is just as dismal as most in the population. However, I understand that the latin prefix/preposition in- is one of those words that are contextual in meaning.

I want to say that Latin in- is like the Hebrew NGD.


Depending on context, it could mean for, against, upon, towards. It could even be inflected to mean overlord, chieftain, leader, governor.

Let me check google translate .... ok, apparently Latin in- could be used in preposition as

  • in
  • into
  • on
  • for
  • at
  • upon
  • among
  • unto
  • till
  • until
  • within
  • against, contra, adverse

Being inadequate in answer, I believe this question should be asked in the Latin forum.

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