Dictionary.com
Thesaurus.com

feldspathoid

American  
[feld-spa-thoid, fel-] / ˈfɛld spæˌθɔɪd, ˈfɛl- /

adjective

  1. Also feldspathoidal of or relating to a group of minerals similar in chemical composition to certain feldspars except for a lower silica content.


noun

  1. a mineral of this group, as nepheline.

feldspathoid British  
/ ˈfɛldspəˌθɔɪd /

noun

  1. any of a group of rock-forming minerals, such as leucite and sodalite, that are similar to feldspars but contain less silica

"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

feldspathoid Scientific  
/ fĕld-spăthoid′,fĕl- /
  1. Any of a group of relatively rare minerals that are chemically very similar to feldspars, but have too little silica to qualify as feldspars. Feldspathoids occur in igneous rocks with little or no silica.


Etymology

Origin of feldspathoid

1895–1900; < German Feldspath ( feldspar ) + -oid