Having practical functions; designed or arranged to perform necessary functions effectively (describes something functional, emphasizing utility).
このリュックは見た目より軽く、収納が多くて機能的だ。
This backpack is lighter than it looks, has lots of storage, and is very functional.
デザインも大事だが、まずは機能的であることが必要だ。
Design is important, but first it needs to be functional.
機能的に問題がなければ、ソフトはそのままリリースできる。
If there are no functional problems, the software can be released as is.