Not my favorite character in the world. Probably the silliest name inflicted on the Doctor Who universe, since they could have just named the girl “Peri” or “Perry” or “Parry” and been done with it.
Anyway, this was apparently a case of Stupid Latin Joke Day at the BBC. The reason nobody talked about it later is apparently because it was dog Latin.
A “pugillus” is a late Latin word that shows up in the Vulgate. Literally it’s a “small fist”. What it really means is a pinch, in English translation of a verse in Proverbs “a small handful”, and in pharmacy stuff, “the amount that can be picked up in three fingers”, probably thanks to a verse in Isaiah.
If there was a feminine form, it’d be “pugilla”, but that actually is Roman for “little butt”. So they might have thought it’d be better spun out as “pugillia”. With the proposition “per”, it’d be “pugilliam”.
So what they were trying to say was “through a small handful”, and it was probably supposed to be the motto of something like a university, and Peri was supposed to sound like her parents were crazy academics (which was basically her background in the show). But I think the show producers eventually decided it wasn’t all that clever, and shut up about it pretty thoroughly. Nothing was ever said about the name in official sources, that I ever heard.
Alternately, they might have been going for a feminine form of “pugil”, boxer, fistfighter, since Peri was supposed to be pugnacious. Or it could have been a notional “pugillia” as meaning “the art of boxing” or “the art of working with small handfuls of stuff”.
UPDATE: Nicola Bryant said this about her character’s name back in Doctor Who Magazine: “Apparently, in the Sixties, mothers in America were naming their children with particularly long ostentatious names. Obviously, John was using this to typify the kind of background that Peri had had, and the kind of mother she had.”
Arrrrrgh. So really her name should have been some rich Eighties chick from Dynasty name, like “Parrington”; or a Sixties name like “Parabola Rainbow Moondancer Galadriel”; but JNT instinctively reached for a different kind of ostentatious and ‘posh’. Well, that explains a lot.