Language Arts Should you use "uninterested" or "disinterested"? This article contains the definitions of uninterested and disinterested and provides a comparison of them. Keep reading for differences in uninterested versus disinterested.

There are a number of negative prefixes in English, partly due to the fact that we have so many words deriving from Old English, French and Latin, and Greek, and each source language had its own set of prefixes, giving us multiple prefixes in English with similar meanings. Because of this, distinguishing between them can be difficult. So let's put un- and dis- in context and see if we can clarify.

The Negative Prefixes of English

Here is a list of the negative prefixes in English, their main meanings, and an example for each:

Prefix	Main Meaning(s)	Example
a- an-	lacking, without	asymmetric
anti-	against, opposite of	antibody
apo-	not	apogamy
contra-	opposing	contrapositive
de-	reverse	deactivate
dis- dif-	opposite of, reverse	disrespectful
in- il- im- ir-	not	inappropriate
mis-	badly, not	mistaken
non-	not	nonstop
un-	not, opposite of	unbelievable

In the cases in which more than one possibility is listed for the prefix, this means that it has several allomorphs - forms it can take on to assimilate better with the root to which is is attached. Since neither dis- nor un- has allomorphs, we won't go into this in more detail here, but if you need further information, there is a section on allomorphs (pages 243-252) in my book Painless Spelling, which is available from Amazon.com.

Un-

There are actually two different negative prefixes un- in English, one related to Old High German un- and the second from Old English un-. In the first case the main negative meanings are “not” or “opposite of” or “contrary to.”  Here are example sentences:

He left the laundry undone.

The U.S. Supreme Court found that the law was unconstitutional.

In the second case, the primary negative meanings of un- are “to reverse or undo,” “to deprive of,” “to remove from,” or “causing to cease to be.” Here are example sentences:

The mother helped her child untie his shoelace, which had gotten into a dreadfully tangled knot.

The minister was unfrocked as a punishment.

Lady Macbeth said, “The raven himself is hoarse

That croaks the fatal entrance of Duncan

Under my battlements. Come, you spirits

That tend on mortal thoughts! Unsex me here,

And fill me from the crown to the toe top-full

Of direst cruelty . . .” in Macbeth Act 1 Scene 5.

The second prefix un- is quite popular, Merriam-Webster.com lists 1050 examples in its online dictionary. In either case, un- is pronounced as /uhn/ (without stress) or /UHN/ (with stress), depending on the context.

Dis-

Fortunately, there's only one prefix dis- in English. It came into Modern English through Middle English from Old French des-, which comes, in turn, from Latin dis-, meaning “apart” or “asunder.” In English, its primary negative meanings are “not,” “absence of,” “opposite of,” “undo,” and “deprive of.” Here are examples:

Don't be so disagreeable: it's only for an hour!

I'm surprised by the disunity voiced here, so let's address that issue first.

Um . . . is it possible to disenchant Alfred so he becomes a guinea pig again instead of a rocking chair?

The subject stated that he was aware at the time that engaging in such behavior could lead to his being disbarred.

Dis- is pronounced /dihs/ or /DIHS/, depending on the context.

Uninterested and Disinterested

The word uninterested, pronounced /uhn IHN trih stihd/ or /uhn IHN tuhr ih stihd/ or /uhn IHN tuhr rehs tihd/, is made by combining the prefix un- with the participle interested. Interested comes through Old French and Middle English from the Latin third person singular present form of interesse, meaning “it is of importance.”  The word disinterested, pronounced /dihs IHN trih stihd/ or /dihs IHN tuh rehs tihd/, is made by combining the prefix dis- with the same form of interest as is used for uninterested.

Uninterested is sometimes used to mean “without any interest,” “not having a financial interest in”-both of which meanings are more generally reserved for disinterested- or “showing a lack of interest.” Here are examples:

The moderator was an uninterested party.*

Peter was uninterested in dinosaurs, but eager to see the mummies.

Disinterested can mean “impartial,” “indifferent” or “having lost interest,” of which the middle meaning used to be the exclusive territory of uninterested. Here are examples:

The moderator was a disinterested party.

Peter was disinterested in dinosaurs, but eager to see the mummies.*

As Abbie grew up, she became disinterested in basketball, and turned to lacrosse.

Historically, the meanings of uninterested and disinterested have slid back and forth. The fact is that some people disapprove of the asterisked uses, but the more important question may be if using the words in these ways could lead to miscommunication. Mistaking someone who is impartial for someone who doesn't care or vice versa in a critical situation could lead to significant misunderstandings.

Differentiating Un- and Dis-

If you are not concerned about the communications issues, you can interchange the words except for “loss of interest” which is a meaning only attached to disinterested. If you wish to keep them separate, using uninterested to mean “not interested,” and disinterested to mean “impartial,” try this mnemonic:

Instead of “impartial,” think of disinterested as meaning “not taking sides.” Connect the prefix dis- with the first three letters of sides in reverse. This leaves uninterested for the alternative meaning of “not interested.”