Noun
perfect cadence (plural perfect cadences)
(music, chiefly UK) A cadence involving the resolution of the dominant chord (V) to the root chord (I).
Synonyms: (chiefly US) authentic cadence, closed cadence
Therefore we well observe that the title of perfect cadence is attached only to a dominant that progresses to the main tone, because this dominant, which is naturally contained within the harmony of the main tone, seems, when it progresses to it, to return as if to its source. Jean-Philippe Rameau