The term doesn't appear in the medical textbook library. Here's what it means based on established Ayurvedic knowledge:

Agnijara (Sanskrit: agni = fire/digestive fire; jara = digesting/old age) refers to a substance or process that is digested by agni (the body's metabolic/digestive fire). More specifically, it is used in two related senses:

In Ayurvedic pharmacology (dravyaguna), agnijara describes substances that are normally considered difficult or impossible to digest, yet are broken down and processed by a sufficiently strong agni (digestive capacity). The concept highlights that the digestibility of a substance depends on the strength of the individual's metabolic fire.

Agnijara is also the name of a specific Ayurvedic mineral/herbo-mineral preparation, sometimes identified with amber or a fossilized resinous substance. In this context it is:

The word builds on agni, the central Ayurvedic concept of digestive and metabolic fire. Impaired agni is considered the root cause of most diseases (rogaḥ sarve'pi mandagnau — all diseases arise from weak agni).

Since this term falls within Ayurveda rather than evidence-based clinical medicine, it isn't covered in standard biomedical textbooks. If you're looking for a specific clinical equivalent or context (e.g., indigestion, metabolism), I can help bridge those concepts.