[ 'mɪəʃɔ:m , -ʃəm ]
■ noun a soft white clay-like material consisting of hydrated magnesium silicate, found chiefly in Turkey.
↘a tobacco pipe with a bowl made from this.
Origin
C18: from Ger., lit. 'sea-foam', translation of Pers. kef-i-daryā (alluding to its frothy appearance).