Difference between inconclusive and non-conclusive (nonconclusive)

Solution 1:

Inconclusive - According to Merriam Webster, Inconclusive means:

• leading to no conclusion or definite result

Neither Merriam Webster nor Oxford Advanced Learners list non-conclusive (or nonconclusive) as a word. So it's most likely that non-conclusive isn't a regular English word (I have never heard of it), rather it is a specialized word used in particular academic or professional disciplines.

From a quick google search I can see, most of the hits that non-conclusive got was from poorly written articles, in many cases from foreign writers. So, even if some people used it as a hyphenated compound word to express the same meaning as inconclusive, it is redundant (and a bit in poor taste.)

Non-conclusive does have some specialized usage as I mentioned. There is a Non-conclusive verb in the progressive tenses. The term was most likely first used by A.S Hornby in his articles and papers in the 1940's and 1950's. These are now generally known as Stative Verbs. Non-conclusive Verb [Journal link]

There is also Non-conclusive Judgment in law. Law-Dictionary

These are the only few usage that I came across. There might be more specialized used in particular fields. But if I wanted to express something that "is leading to no conclusion/definite result" I would stick to inconclusive.

Solution 2:

The Oxford on-line dictionary gives two principle meanings of "conclusive". These are

the end or finish of an event, process, or text

and

a judgement or decision reached by reasoning.

Broadly, inconclusive is commonly used in opposition to the second meaning. We say that the evidence was inconclusive, meaning that it was insufficient to allow a definite judgement to be made. The meeting was inconclusive if no decision could be made.

Non-conclusive is in opposition to the second meaning. Something is non-conclusive if it is not the end of the matter.

As Rio1210 has identified non-conclusive is used in law regarding a judgement that is subject to appeal. The decision of the court is non-conclusive because it is not the end of the matter, or not necessarily the end of the matter.

The meeting came to a decision, but it is non-conclusive because it still has to go to the board.