schlieren
Concise Oxford English Dictionary © 2008 Oxford University Press:
schlieren /ˈʃlɪərən/
▶plural noun
- 1 technical discernible layers in a transparent material that differ from the surrounding material in density or composition.
- 2 Geology irregular streaks or masses in igneous rock.
– origin C19: from Ger. Schlieren, pl. of Schliere ‘streak’.
'schlieren' also found in these Oxford entries:

