(1) Patricius, plural Patricii, is simply a Latin word derived from pater or father, indicating the Roman nobility; that is patrician.
In the latter empire, under the reign of Constantine patricius became a non-hereditary personal title conferred by the emperor. This was a title of very high rank that gave the grantee certain privileges, and came in two flavours,
- the patricii praesentales for those who where engaged in actual service
- the patricii codicillares or honorarii for whom it was only an honorary title
With the collapse of the Roman Empire in the west during the fifth century their successors continued the use of Roman titles to bolster their claims to legitimacy. (Hence the continuation of other Roman titles such as comes or count and dux or duke.) Popes and kings, emperors and assorted tyrants were in the habit of giving to their most distinguished subjects the title of patricius. So that Charlemagne for example, had the title Patricius Romanus as protector of the Holy See.
In particular within the British kingdom of Northumbria, patricius seems to be a title conferred by the king on his most senior and trusted advisor, the highest in rank within the kingdom after the king himself.
(2) Patricius is also the name that one Magonus Sucatus assumed after his ordination as a priest. He became better known as Saint Patrick and hence Patricius is often quoted as the Latin form of the name Patrick.
SOURCES
A Biographical Dictionary of Dark Age Britain by
Ann Williams, Alfred P Smyth and DP Kirby (Seaby, 1991)
A Dictionary of Greek and Roman Antiquities by William Smith (John Murray, 1875)