Autocorrect is one feature of the iPhone that users love to hate. Sometimes the keyboard dictionary helps speed up typing. Other times there are more failures than successes. Over time iOS automatically adds words to its dictionary. Once the iPhone gathers custom words you have typed, they are corrected or suggested in predictive text buttons.
If you're getting odd spelling suggestions when you type on your iOS keyboard you can reset your dictionary to factory defaults and start all over. This is helpful to erase "learned" misspelled words, joke spellings, common typos and words you have typed in a foreign language. Unfortunately there is no way to edit single words in iOS. You instead have to reset everything or create your own word shortcut.
One of the more useful built-in features of iOS is the dictionary. Looking up words on the iPhone is easy with a long press or by using 3D Touch. Since the launch of iOS 12, Apple has added a new feature to the built-in dictionary. Users can quickly access a thesaurus as well. This makes it possible to find similar words or synonyms that are related to the target word.