Connected with perna (“ham, haunch”), though the expected form would be *pernāx.[1][2]
pernīx (genitive pernīcis, comparative pernīcior, superlative pernīcissimus, adverb pernīciter); third-declension one-termination adjective
According to Döderlein, celer and citus mean "swift, fast, quick" in terms of quick motion (in general) with tardus as their antonym. More specifically, citus refers to a lively motion, whereas celer refers to an eager or impetuous motion.
On the other hand, pernīx and vēlōx as "quick" denote a level of athletic nimbleness in terms of bodily activity, with lentus as their antonym. More specifically, pernīx involves a level of dexterity and quickness in an eclectic range of actions (such as climbing, hurdling, jumping, vaulting, etc.); whereas vēlōx is especially used for running, swimming and flying (moving in a direction)
Thirdly, properus and festīnus as "quick" refer specifically to one's speed in terms of the shortest time to reach a destination, with sēgnis as their antonym. More specifically, festīnus intimates a certain level of impatience, whereas properus simply indicates a haste from energy simply.
Third-declension one-termination adjective.
Number | Singular | Plural | |||
---|---|---|---|---|---|
Case / Gender | Masc./Fem. | Neuter | Masc./Fem. | Neuter | |
Nominative | pernīx | pernīcēs | pernīcia | ||
Genitive | pernīcis | pernīcium | |||
Dative | pernīcī | pernīcibus | |||
Accusative | pernīcem | pernīx | pernīcēs | pernīcia | |
Ablative | pernīcī | pernīcibus | |||
Vocative | pernīx | pernīcēs | pernīcia |