Two dictionaries give different origins for OK, how do I decide which to trust Discussion

The general method matters more than this particular word, so here's how I'd rank sources when they disagree.

First, prefer sources that quote dated texts over sources that assert. A claim with a newspaper name and a date can be checked. A claim that says probably from an African language cannot.

Second, look for the earliest attestation and ask whether the proposed origin can explain it. If your explanation requires the word to exist in 1790 and nobody can produce it in print before 1839, the explanation has a hole in it.

Third, check whether the story explains the form as well as the meaning. Lots of proposals give you a plausible sound and no account of why it was written as two capital letters.

On OK specifically, the 1839 Boston newspaper trail is the one with actual dated citations behind it. It came out of a short-lived fashion for jokey abbreviations of deliberately misspelled phrases, and it then got a huge boost the following year when a political club adopted the same two letters for unrelated reasons. That double origin is part of why it stuck when the other abbreviations from the same fad died.

The competing proposals are not absurd, they're just unattested. That's the difference to hold onto.

Free tools that will get you a long way:

• Your public library card very often includes remote access to a major dictionary, worth ten minutes checking
• Etymonline, which is free and generally flags disputes rather than hiding them
• Google Books with a date range, but treat the dates with suspicion because the metadata is frequently wrong and periodicals get bound with the wrong year
• Free newspaper archives, which is where a lot of antedating actually happens now

The metadata warning is not a small thing. Half the confident finds people post turn out to be a 1911 reprint catalogued as 1847.

One more filter: who benefits from the story. Origins that flatter a nation, a trade or a subculture spread faster than boring ones, and you'll notice the confident competing claims for OK each attach it to a group with a stake in it. Doesn't make them wrong, does make me want the citation first.

Also accept that some words just end in unknown, and that a dictionary saying origin uncertain is being honest rather than lazy. The urge to have a clean answer for everything is what keeps the folk versions in circulation.