evanescent

Consequently, the electromagnetic fields have plane-wave characteristics in local regions, except immediately adjacent to a caustic where there is a rapid transition from the wavelike behavior of the local plane-wave fields to the evanescent behavior beyond the ray path.

[…] I choſe rather to reduce the demonſtrations of the following propoſitions to the firſt and laſt ſums and ratio's of naſcent and evaneſcent quantities, that is, to the limits of thoſe ſums and ratio's; […] Perhaps it may be objected, that there is no ultimate proportion of evaneſcent quantities; becauſe the proportion, before the quantities have vaniſhed, is not the ultimate, and when they are vaniſhed, is none. […] [B]y the ultimate ratio of evaneſcent quantities is to be underſtood the ratio of the quantities, not before they vaniſh, nor afterwards, but with which they vaniſh.

If the Fluids moving in an Evaneſcent Artery [i.e., a capillary] appear Globular, I ſuppose its becauſe the Canal is round, which alters the Caſe much.

Upward it [the "apennine adonis", probably the Pyrenean pheasant's eye (Adonis pyrenaica)] is of a pale green, with ſome Tinge of yellowiſh; and it is all the Way duſted with little grey tranſparent Globules. Theſe are the Extremities of ſo many round evaneſcent ſecretory Ducts; as the Hairs of other Plants are the more permanent Extremities of theirs.