noun Petrology.
  1. a fine-grained gabbro occurring as minor intrusions.
  2. British. a dark igneous rock consisting essentially of augite and feldspar; an altered dolerite.

Origin of diabase

1810–20; < French, equivalent to dia- (error for di- two) + base base1
Related formsdi·a·ba·sic, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for diabase

Historical Examples of diabase

British Dictionary definitions for diabase


  1. British an altered dolerite
  2. US another name for dolerite
Derived Formsdiabasic, adjective

Word Origin for diabase

C19: from French, from Greek diabasis a crossing over, from diabainein to cross over, from dia- + bainein to go
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

diabase in Science


  1. A dark-gray to black, medium-grained igneous rock consisting mainly of labradorite and pyroxene. Diabase is compositionally similar to andesite, but has coarser grains. It is commonly found in sills and dikes. Also called dolerite
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