ag‧glom‧er‧ate/əˈɡlɒmərət, əˈɡlɒmərɪt $ əˈɡlɑː-/ noun[SINGULAR, UNCOUNTABLE] technical [date : 1600-1700; Language : Latin; Origin : past participle of agglomerare 'to pile up', from ad- 'to' glomus 'ball'] a type of rock formed from pieces of material from a volcano that have melted together