A female name. Latin f. diminutive of Petronius, the name of a Roman gens, possibly a derivative of petra ‘stone’. The discovery of a tomb in Rome, inscribed Filiae dulcissimae Aureliae Petronillae, led to the belief that Petronilla was the name of a d. of St Peter, and, as St Petronilla, she was invoked against fevers. The name was very common in the Middle Ages, when it was used as a convenient f. form of Peter. It is found in England from the 12th C and was early contracted to Peronel, Pernel, or Parnel (cf. the surnames Parnall, Parnell, Parnwell). Pernel or Parnel, for some reason, came to be used as a generic name for a priest’s concubine, and is so used as early as 1362 in Piers Plowman. Later it meant any loose woman, and survived in dialectal use until the 18th C. The christian name Parnel or Peternel survived in Cornwall and Lancashire till the 18th C.

Petronilla Curia Regis Rolls 1196, Hundred Rolls 1273, Feudal Aids 1303, 1316. Petronella Curia Regis Rolls 1207, Feudal Aids 1303. Petronyl English Register of Godstow Nunnery, c. 1450 (E.E.T.S. 129-30) 1450. Pernel Hundred Rolls 1273. Parnell Lincs 1529, Church Registers of St. Mary Aldermary, 1558-1754 1680. Paronel Yorks Poll Tax of West Riding of Yorkshire 1379 1379. Peternell Major Church Registers of St. Columb Major 1706. Petronel Major Church Registers of St. Columb Major 1714.