Definition of diabase in English:



  • another term for dolerite
    • ‘It is also a widespread constituent of a variety of igneous and metamorphic rocks and is occasionally found in pegmatites and in related veins marginal to igneous rock units ranging from granite to diabase.’
    • ‘If natural stone, such as basalt or diabase, is used, the product is called rock wool.’
    • ‘The lower series consists of alternating basalt lava, tuff breccia, tufite, and siliceous rock, whereas the upper one is dominated by diabase.’
    • ‘Intrusion of diabase at Mt. Butters has resulted in low-grade contact metamorphism of the pre-existing sedimentary strata.’
    • ‘Many such dikes in western Maine are classified as alkali diabase.’


Mid 19th century (originally denoting diorite): from French, formed irregularly as if from di- ‘two’ + base ‘base’ (thus ‘rock with two bases’, referring to the base minerals of diorite), but associated later perhaps with Greek diabasis ‘transition’.