LATIN DICTIONARYLexicon Latīnum
adjectivethird-declension two-termination adjective

perfidēlis

perfidēlis (neuter perfidēle, comparative perfidēlior, superlative perfidēlissimus, adverb perfidēliter)
Classical[pɛr.fɪˈdeː.lɪs]Ecclesiastical[per.fiˈdɛː.lis]

Meaning

  1. two terminationvery faithful, very loyal
  2. two terminationvery true, very trustworthy, very dependable, very trusty
    posthac ad te aut, si perfidelem habebo cui dem, scribam plane omniaIn future letters I shall either put everything down in plain terms, if I get hold of a very trustworthy messenger68 BCE – 44 BCE, Cicero, Epistulae ad Atticum 2.19.5

Declension

singular
formmasculinefeminineneuter
nominativeperfidēlisperfidēlisperfidēle
genitiveperfidēlisperfidēlisperfidēlis
dativeperfidēlīperfidēlīperfidēlī
accusativeperfidēlemperfidēlemperfidēle
ablativeperfidēlīperfidēlīperfidēlī
vocativeperfidēlisperfidēlisperfidēle
plural
formmasculinefeminineneuter
nominativeperfidēlēsperfidēlēsperfidēlia
genitiveperfidēliumperfidēliumperfidēlium
dativeperfidēlibusperfidēlibusperfidēlibus
accusativeperfidēlīs
perfidēlēs
perfidēlīs
perfidēlēs
perfidēlia
ablativeperfidēlibusperfidēlibusperfidēlibus
vocativeperfidēlēsperfidēlēsperfidēlia

per-fĭdēlis, e, adj.,
I. very trusty, very faithful: homo, Cic. Att. 2, 19, 5: perfidelis in amicos, Aur. Vict. Caes. 13, 8.

Origins

From per- + fidēs (“faith, trust”) + -ēlis.

Quick answers

What does perfidēlis mean in Latin?
perfidēlis, a adjective, means “very faithful, very loyal; very true, very trustworthy, very dependable, very trusty”.
How do you pronounce perfidēlis?
In classical Latin, [pɛr.fɪˈdeː.lɪs]; in ecclesiastical (church) Latin, [per.fiˈdɛː.lis].