[after RED GUM1, q.v.] An eruption of whitish spots with a red border (Strophulus albidus) incident to young children.

1

1799.  Underwood, Dis. Childhood (ed. 4), I. 81. Another species [of Red-gum] … often of a pearl colour and opake, which has generally been accounted a kind of red gum, but it has of late been suggested might … be termed the white-gum.

2