definieren
to define
To determine and explain the exact meaning of a word, concept, or matter.
Können Sie den Begriff „Nachhaltigkeit“ bitte genauer definieren?
Could you please define the term “sustainability” more precisely?

to define
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to define
To determine and explain the exact meaning of a word, concept, or matter.
Können Sie den Begriff „Nachhaltigkeit“ bitte genauer definieren?
Could you please define the term “sustainability” more precisely?

The related noun is 'die Definition' (the definition). When you 'definieren' (define) something, you create a definition.
Die Definition dieses Begriffs ist sehr komplex.
The definition of this term is very complex.
To explain what something is, 'definieren' (to define) is often used with the preposition 'als' (as). The structure is: etwas (accusative) als etwas definieren (to define something as something).
Man kann Intelligenz als die Fähigkeit zum logischen Denken definieren.
One can define intelligence as the ability to think logically.
When it is about establishing things, 'definieren' (to define) is often combined with abstract nouns such as 'Ziele' (goals), 'Grenzen' (boundaries), 'Regeln' (rules), or 'Anforderungen' (requirements).
Vor Projektbeginn müssen wir die genauen Anforderungen definieren.
Before the project begins, we need to define the exact requirements.
In the meaning 'seine Identität ableiten' (to derive one's identity), the verb is reflexive and is always used with the preposition 'über' and the accusative: sich über etwas definieren (to define oneself by something).
Viele junge Menschen definieren sich stark über ihre Freunde und ihre Musik.
Many young people define themselves strongly by their friends and their music.
to explain / declare
'erklären' and 'definieren' can both mean making something understandable. 'erklären' is more general: you describe how something works, why something happens, or what someone should do. 'definieren' is more precise: you establish the exact meaning of a word or concept, or clearly delimit something. Learners may confuse the words because defining something often also involves explaining it. But not every explanation is a definition. In class, everyday life, or instructions, 'erklären' often fits; for concepts, rules, and clear boundaries, 'definieren' is better.

Im Kurs definieren wir zuerst den Begriff „Demokratie“.
In the course, we first define the term “democracy.”
Kannst du mir bitte erklären, wie der Drucker funktioniert?
Can you please explain to me how the printer works?