WordPress Proofread Writing function available through Jetpack
Most blogging platforms provide basic spell-check functionality. If you’re using WordPress 3.6 or beyond, the spell-check is built into the Jetpack plugin and is accessed through the Proofread Writing button, as shown above. Many third-party plugins and browser-based add-ons also provide spell checking. However, the underlying technology supporting these functions changes frequently; therefore, the source dictionaries also change.
Rather than rely on the whims of developers (whom we bloggers still very much appreciate), choose a master dictionary that you can reference any time spell-check gives you a questionable suggestion.
Regular home and office dictionaries will usually suffice for general use; however, collegiate (college) and unabridged dictionaries are the best choice because they are much more comprehensive in both the number of words included and the depth of each entry.
If your readers are primarily North American, consider the most recent versions of Merriam-Webster’s Collegiate Dictionary or The American Heritage College Dictionary. If your readers are largely English speakers outside of North America, consider the Oxford Dictionary of English.
And if you don’t have room on your desk for a giant tome, you can also subscribe to the complete online version of Merriam-Webster Unabridged or the Oxford English Dictionary. The American Heritage College Dictionary doesn’t have a premium online subscription service, but it does offer paid Android and iOS apps.