What is "aeger"

a. 1 (context dated British school slang English) Absent and excused from one’s classes due to illness 2 (context dated British school slang English) Relating to such an excused absence n. 1 (context dated British school slang English) An excused absence from classes due to illness 2 (context dated British school slang English) A note excusing a student from classes due to illness

Aeger is a genus of fossil prawns. They first occur in the Middle Triassic, and died out at the end of the Late Cretaceous. A total of 20 species are known.