What 5 letter word can be read the same upside down?

When you use capital letters, SWIMS can be read the same upside down.

Note: Nabisco had a snack mix called 'doodads' (now discontinued), which they spelled on the box in all lower case letters. If you placed the box upside down in the cupboard, it read 'spapoop' so our family started calling them 'spapoops'. That was many, many years ago, and still today, I had to stop and figure out what that real name was.