(meteorology, informal) A powerful hurricane or other major weather disturbance, especially as produced by a combination of meteorological conditions.

plural of perfect storm

(music) an interval equal to that of between the second and third harmonics of the harmonic series; in equal temperament, an interval of seven semitones spanning five degrees of the diatonic scale. It is enharmonically equivalent to a diminished sixth.

(video games, design) Involving precision at the pixel level. / (computing, design) Having precise dimension ratios in all aspects on well-defined drawing glyphs.

(mathematical analysis) A set which is equal to its set of limit points. That is, a set A is perfect if A'=A.

plural of perfect number

plural of perfect game

(music) A musical interval of the Western twelve-semitone system consisting of twelve semitones and spanning eight degrees of the diatonic scale. It is enharmonically equivalent to an augmented seventh and is commonly referred to as an octave.

plural of perfective aspect

Used when someone's mistakes or flaws are acknowledged, to remind that everyone else makes mistakes and has flaws.