funktionell
functional
Related to function; designed in a practical and purposeful way, without unnecessary decoration.
Die neue Küche ist sehr modern und funktionell eingerichtet.
The new kitchen is furnished in a very modern and functional way.

functional
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functional
Related to function; designed in a practical and purposeful way, without unnecessary decoration.
Die neue Küche ist sehr modern und funktionell eingerichtet.
The new kitchen is furnished in a very modern and functional way.

'Funktionell' (functional) is the adjective related to the noun 'die Funktion' (function) and the verb 'funktionieren' (to function/work). All words in this family refer to the purpose or way something works.
Die Hauptfunktion dieser App ist die Terminplanung.
The main function of this app is appointment scheduling.
In the meaning 'zweckmäßig' (practical/functional), 'funktionell' (functional) is often used to describe design, furniture, architecture, or clothing. It emphasizes practical usability.
Für die Wanderung brauche ich vor allem funktionelle Kleidung.
For the hike, I mainly need functional clothing.
You can recognize the medical meaning from the context. It always appears in connection with illnesses or complaints and is often contrasted with the word 'organisch' (organic).
Der Patient leidet an einer funktionellen Magen-Darm-Störung.
The patient suffers from a functional gastrointestinal disorder.
When 'funktionell' (functional) describes a disorder, it is a medical technical term. It means that the function is impaired, but the organ itself appears healthy.
Viele Patienten mit funktionellen Beschwerden fühlen sich nicht ernst genommen.
Many patients with functional complaints feel that they are not taken seriously.
practical / virtually
'praktisch' and 'funktionell' both describe something as well suited for a purpose. 'praktisch' is a very general everyday word: something is useful, convenient, or helpful in a situation. 'funktionell' sounds more factual and often describes the design of things, rooms, or clothing. It emphasizes that function is more important than decoration or beauty. The words can be confused because both speak positively about usefulness. In normal everyday situations, 'praktisch' usually sounds more natural. 'funktionell' fits better when the topic is practical design or clear functions.

Die neue Arbeitskleidung ist funktionell und hat keine unnötigen Verzierungen.
The new work clothing is functional and has no unnecessary decorations.
Diese Tasche ist praktisch, weil sie viele kleine Fächer hat.
This bag is practical because it has lots of small compartments.