Burro and Burrow are easily confused words. The spell-check application of most word processing software programs would not catch a slip-up of these two words. Spell-check is looking for words that aren’t in its dictionary, and words that resemble words in its dictionary but are possibly spelled wrong. Spell-check isn’t perfect. It doesn’t know and can’t guess what word you wanted or what word you meant, it can only judge the words on the page. If you used words that are all spelled correctly, it gives you a pass anyway. Similarly, autocorrect on mobile phones might suggest one word instead of the other, it would be easy to do since both words start with “b-u-r-r-o.”
Burro is a noun. It’s a Spanish word meaning a small donkey used as a pack animal.
Burrow is a verb. It’s when a creature digs a hole big enough for it to conceal it’s entire body in. Moles, groundhogs, and ghost crabs are just three of many creatures that are famous for their burrowing skills.
The following sentence uses both words correctly:
Bernard was an unusual burro, when he didn’t feel well he would burrow into the ground and wedge himself in the hole, head first.