I. ˈhī-ə-lən, -ˌlīn adjective
Etymology: Late Latin hyalinus, from Greek hyalinos, from hyalos
Date: circa 1661
: transparent or nearly so and usually homogeneous
II. ˈhī-ə-lən, -ˌlīn, in sense 2 -lən or -ˌlēn noun
Date: 1667
1. : something (as the clear atmosphere) that is transparent
2. or hy·a·lin -lən : any of several translucent nitrogenous substances related to chitin, found especially around cells, and readily stained by eosin