functional
working or serving a purpose
Root
- funct: perform, carry out, or discharge a duty
Other words with the funct root
- function: purpose, role, or performance
- functionary: official who performs a role, often routinely
- perfunctory: done with little care or merely as routine
Functional means able to perform its job.
The first prototype was ugly but functional.
It may not be elegant; it does the work it was built for.