1. Plural of flatty; flat-soled shoes or sneakers, especially casual footwear with minimal heel.
Usage: informal; chiefly British
2. Plural of flatty; flat fish, such as flounder or sole.
Usage: informal; nautical/fishing

Examples

• She prefers wearing flatties to work because they're more comfortable than heels.
• The store has a great selection of flatties in different colors and styles.
• For the beach trip, I packed my flatties and sandals.
• The fishermen caught several flatties in their nets this morning.
• Flatties are practical shoes for people who spend a lot of time on their feet.