nummulitePronunciation: /ˈnʌmjʊlʌɪt/Definition of nummulite noun Palaeontology the flat disc-shaped calcareous shell of a foraminiferan, found commonly as a fossil up to 8 cm across in marine Tertiary deposits. Family Nummulitidae, order Foraminiferida: several genera, including Nummulites Origin: early 19th century: from Latin nummulus (diminutive of nummus 'coin') + -ite1nummulite in other Oxford dictionaries Definition of nummulite in the US English dictionary