Definition of "schlieren" []

• Geology Irregular dark or light streaks in plutonic igneous rock that differ in composition from the principal mass. (noun-plural)
• Regions of a transparent medium, as of a flowing gas, that are visible because their densities are different from that of the bulk of the medium. (noun-plural)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "I have some old schlieren photos in my office showing you how terrible."
• "Just schlieren video showing variation in the refractive index of fluids due to changes in density with temperature."
• "Researchers measured the wake of the rotor using a technique known as retro-reflective background oriented schlieren."