noun
chapter
B1
Kapitel (das) means chapter (a section of a book) and can be used figuratively for phases. Plural is Kapitel (unchanged). Genitive singular often adds -s: des Kapitels. It's a neuter noun with regular declension otherwise; plural form is identical to singular, so context or article shows number.
Examples
Der Autor schrieb ein neues Kapitel, nachdem der Verlag zusätzliche Informationen geliefert hatte.
The author wrote a new chapter after the publisher had provided additional information.
Dieses Buch hat zwölf Kapitel.
This book has twelve chapters.
Das Kapitel beginnt mit einer spannenden Szene am Strand.
The chapter begins with an exciting scene on the beach.
Details
Mnemonics
Imagine a book open to the beginning of a new chapter with a big Roman numeral at the top.
Sounds like 'capital' (think of the main section of a book like a capital section).
das (neuter) — think of a little neutral label 'das' stamped on the book's cover.
Notes
Plural is unchanged: Kapitel. Common in both fiction and textbooks; genitive singular often shows -s: des Kapitels.