cup-gall

from The Century Dictionary.

• noun A singular kind of gall found on the leaves of the oak and some other trees, of the figure of a cup, or a drinking-glass without its foot, adhering by its point or apex to the leaf, and containing the larva of a small fly. The insect which makes cup-galls is Cecidomyia poculum.

from the GNU version of the Collaborative International Dictionary of English.

• noun A kind of oak-leaf gall. See gall.