Here's the quickest way to “teach” autocorrect new words.
How to add new words to iOS dictionary Simply open up Safari and type the word in the smart search field. Once you’ve done that, iOS should stop correcting that word for you.
Of course, you could instead add the word to the shortcuts list (which syncs across all your devices) from Settings > General > Keyboards > Shortcuts, but searching in Safari is much quicker.
There are other methods as well to teach iOS new words, check it out if this doesn’t work for you.
The nice thing is that, the dictionary gets synced across iOS devices, so if you successfully add a word, it should get synced across all your devices.
Let us know if this tip helped you....