For today’s blog: Disinterested or uninterested? Which is it and when? 
The primary meaning of “disinterested” (Oxford English Dictionary) is “impartial,” or “not interested by considerations of personal advantage.” But, very surprisingly, its earliest recorded sense is “not interested” (i.e. a synonym for “uninterested”).
Using “disinterested” to mean uninterested is widespread, but the OED says it “should be avoided in careful writing.”
In Garner’s Modern American Usage, etymologist Bryan Garner distinguishes between the nouns, “disinterest” and “uninterest”: For “disinterest,” he cites “(1) impartiality or freedom from bias or from chance of financial benefit [‘the judge showed disinterest in the way every judge should’].”
Garner also cites the other use: “(2) lack of concern or attention [‘the team suffered from the disinterest of their traditional supporters]” (Garner 260).
Of this distinction, he writes that “leading writers and editors almost unanimously reject sense 2, in which uninterest . . . is the better term, because it’s unambiguous” (Garner 260). These writers and editors he refers to as “traditionalists.”
Garner writes that “given the overlapping nouns [“disinterest” and “uninterest”], . . . writers have found it difficult to keep the past-participial adjectives [“disinterested” and “uninterested”] entirely separate, and many have given up the fight to preserve the distinction between them.”
But he adds this: “the distinction is still the best recognized and followed because ‘disinterested’ captures a nuance that no other word quite does. Many influential writers have urged preservation of its traditional sense.”
Garner says that usage expert A.R. Orage “rhapsodied over” the term, “disinterested.” Orage wrote in 1922 that “ ‘ No word in the English language is more difficult [than disinterested] to define or better worth attempting to define. . . . it contains all of the ideas of ethics and even, I should say, of religion . . . . whoever has understood the meaning of ‘disinterestedness’ is not far off understanding the goal of human culture’ ” (Orage 29).
Garner doesn’t make as large a claim for the word. But he gives several examples where incorrect use detracts from the writing in question. Here’s just one: “ ‘On a day when seeded [tennis] players fell by the wayside like overripe tomatoes, Agassi looked sickly and almost disinterested [should read: “uninterested”]’ ”(George Gross, “Mighty Have Fallen,” Toronto Sun 25 June, 1996, p. 67; in Garner 261).
If, in business or academic writing, you’re aiming for unambiguous meaning, I’d recommend taking the traditionally favoured definitions of “disinterest” and “disinterestedness.”
A thought for today: “After watching the nightly news for a week, I was uninterested in the details that indicated that Harper was no disinterested player in the Mike Duffy/Nigel Wright scandal.”
Do you have a lexical or grammatical bugbear? Please send it to me on my “contact” page. I’d be happy to discuss it with you and/or to include it in my next blog or e-newsletter.