What does auceps syllabārum mean in Latin?

auceps syllabārum, a noun, means “a person who quibbles over words, argues over semantics or other technicalities; a pettifogger”.

What is the genitive of auceps syllabārum?

The genitive singular is aucupis syllabārum. auceps syllabārum is third declension.

In classical Latin, [ˈau̯.kɛps syl.laˈbaː.rũː]; in ecclesiastical (church) Latin, [ˈaːu̯.t͡ʃeps sil.laˈbaː.rum].

nounthird declension

auceps syllabārum m (genitive aucupis syllabārum)

Classical[ˈau̯.kɛps syl.laˈbaː.rũː]Ecclesiastical[ˈaːu̯.t͡ʃeps sil.laˈbaː.rum]

derogatoryhumorousa person who quibbles over words, argues over semantics or other technicalities; a pettifogger
Ita est tibi iūris cōnsultus ipse per sē nihil nisi lēguleius quīdam cautus et acūtus, praecō āctiōnum, cantor fōrmulārum, auceps syllabārum.And as a result, a lawyer in and of himself ends up being merely some kind of diligent and shrewd legal tradesman, a crier of legal actions, a singer of legal formulas, a trapper of syllables.55 BCE, Cicero, De oratore 1.236.7

From auceps (“bird-catcher”) + syllabārum (“of syllables”).