Mid 18th century; earliest use found in Philosophical Transactions of the Royal Society of London. From classical Latin pectunculus small scallop from pectin-, pecten scallop + -culus; compare -cle.
Definition of pectuncle in US English:
pectuncle
nounˈpɛkˌtʌŋkl
rare
A cockle.
Origin
Mid 18th century; earliest use found in Philosophical Transactions of the Royal Society of London. From classical Latin pectunculus small scallop from pectin-, pecten scallop + -culus; compare -cle.