dol·er·ite (dŏl'ə-rīt') n.
Chiefly British A dark, fine-grained igneous rock; diabase.
[French dolérite, from Greek doleros, deceitful (from its easily being mistaken for diorite), from dolos, trick; see del-2 in Indo-European roots.] dol'er·it'ic (ə-rĭt'ĭk) adj.