Used independently of any style, this option influences a single word and nothing else: if you select a word and disable Spelling for this particular (instance of a) word, it won’t be hyphenated.

This can prove very useful, when you find that hyphenation leaves a single letter on a different line!

I even created an icon in my Quick Access toolbar to easily deactivate Grammar and Spell Check, thus disabling hyphenation for particular words. My hyphenation zone is the strongest that Word allows, but this may cause the orphan letters problem.

To find this option use Command Search (“Tell me what you want to do…”). Write “language” and go to “Set Proofing Language”. Then disable Spelling and Grammar Check.

Your choice influences only this instance of the selected word; Grammar and Spelling Check remains active for the rest of your document as before.