"Pleno titulo" (abbreviation P.T.) is a Latin expression for "by full title(s)", associated with a given person if you do not know all the individual's titles. Could be used for mailing something to somebody by post, for instance as: P.T. John Smith, if you do not know or are not sure about all the possible John Smith's titles.
I do however think it is not much used in English language.
Milan Bily
Pleno titulo גרמנית הגייה עם משמעויות, מילים נרדפות, הפכים, תרגומים, משפטים ועוד.