littera canina

• (Classical Latin) IPA^(key): [ˈlɪt.tɛ.ra kaˈniː.na]
• (modern Italianate Ecclesiastical) IPA^(key): [ˈlit̪.t̪e.ra kaˈniː.na]

littera canīna f (genitive litterae canīnae); first declension

1. the letter R (literally dog's letter, after its trilled pronunciation in Latin)
   • c. 62 CE, Persius, Saturae 1.108–110:

     Vide sis ne maiorum tibi forte limina frigescant: sonat hic de nare canina littera.

     Take care the thresholds of the great don’t grow chilly towards you: this is where you’ll hear the snarl of a dog’s rrrr.

First-declension noun with a first-declension adjective.