1. The first five books of the Old Testament.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• oentateuch,
• lentateuch,
• -entateuch,
• 0entateuch,
• pwntateuch,
• psntateuch,
• pdntateuch,
• prntateuch,
• p4ntateuch,
• p3ntateuch,
• pebtateuch,
• pemtateuch,
• pejtateuch,
• pehtateuch,
• pentatech,
• pentatuech,
• pantateuch,
• heptatech,
• heptatteuch,
• Heptiteuch

• pentathlete,
• pentothal,
• pentode,
• pentathlon,
• pentatonic.

The adjective form of the word "pentateuch" is "pentateuchal".

The plural form of the word "pentateuch" is "pentateuchs".

The singular form of the word "pentateuch" is "pentateuch". The word itself does not change when referring to a single version or instance of it.