Not to be discerned; imperceptible; not discoverable
or visible.
1. (Zoöl.) One of the brachyuran Crustacea. They are mostly marine, and usually have a broad, short body, covered with a strong shell or carapace. The abdomen is small and curled up beneath the body. Note: The name is applied to all the Brachyura, and to certain Anomura, as the hermit crabs. Formerly, it was sometimes appli...