1. an introduction to a subject of study, especially a systematic introduction to a branch of knowledge or a text
Usage: formal; chiefly academic or scholarly
2. a work that serves as an introductory guide to a field of study or a particular text
Usage: formal; historical or academic

Examples

• The professor assigned an isagoge to ancient philosophy before diving into Plato's dialogues.
• This isagoge to medieval theology provides essential background for understanding scholasticism.
• The textbook serves as an isagoge for students new to the discipline of logic.
• An isagoge to classical rhetoric helps readers appreciate the techniques used by ancient orators.
• The author wrote an isagoge explaining the historical context of the manuscript.