1. designed to be practical and useful rather than attractive
2. working or operating correctly
3. relating to the way something works or operates

Examples

• The kitchen has a functional design with plenty of storage space.
• After repairs, the elevator is now fully functional.
• She prefers functional clothing over fashionable outfits.
• The new software update made the app more functional.
• The architect focused on creating a functional office layout.
• Is your computer functional after the virus removal?
• They chose functional furniture for the small apartment.