Perfect Participle

Caesar captam urbem incendit.
Caesar burnt the captured city.

As you can see, perfect participles in both English and Latin are passive—the city is the object rather than the subject of the act of capture.

I don't think Latin perfect participles show up in English very often, but when they do, here's how it works. The perfect participle is derived from the supine, with the suffix “-um” changed to an adjectival suffix, generically the masculine singular “-us”. Then, when the participle comes over to English, the suffix is dropped.

capio	I take	captus	capt (?)
rapio	I seize	raptus	rapt
compono	I place together	compositus	composite

By the way, dropping the suffix “-us” is a good general rule, applicable to nouns as well as adjectives, but there are exceptions, like “fungus”.

What about the discrepancy between “capt” and “captured”? Basically, that was just an unfortunate example, but if you're curious, here's the story. The verb “capio” apparently never made it into English, but the noun “captura”, derived from the future participle “capturus”, did. The verb “to capture”, according to my dictionary, came from that noun.

It isn't just in grammatical jargon that “perfect” has to do with being finished. The word “perfect” is the perfect participle of the verb “perficio”, which in turn is a compound of the prefix “per-”, meaning “thoroughly” or “to the end”, and the verb “facio”, “I do”. So, “perfect” literally means “done to the end”. D'oh!