noun
reason, basis, ground
B1
Noun 'Grund' (masculine): means reason, basis or ground. Plural 'Gründe' (umlaut + -e). Genitive singular often 'des Grundes'. Special note: commonly used with 'Grund für + Akk.' (e.g., Grund für die Entscheidung). Used in many set phrases. No unusual declension beyond the plural.
Examples
Ich habe einen Grund.
I have a reason.
Die Jury nannte keinen Grund, warum der Antrag abgelehnt wurde, obwohl die Begründung verlangt worden war.
The jury gave no reason why the application was rejected, although an explanation had been requested.
Die Basis der Theorie ist ein einfacher mathematischer Grundsatz.
The basis of the theory is a simple mathematical principle.
Details
Mnemonics
picture the foundation (ground) of a house — the basis for everything
think 'ground' in English (Grund ~ ground)
der: imagine a strong male figure holding the 'Grund' (masculine)
Notes
Grund is very versatile: it can mean 'reason', 'basis', or physical 'ground' depending on context. Genitive forms 'des Grundes' or colloquial 'des Grunds' are both used.