LATIN DICTIONARYLexicon Latīnum
adverb

potissimum

potissimum (not comparable)
Classical[pɔˈtɪs.sɪ.mũː]Ecclesiastical[poˈtis.si.mum]

Meaning

  1. not comparablechiefly, above all
    Socero igitur generoque suffragantibus ex omni provinciarum copia Gallias potissimum elegitBacked therefore by his father-in-law and son-in-law, of the whole of abundance of provinces he chose Gaul above all121 CE, Suetonius, De vita Caesarum Vita divi Iuli 22

Charlton Lewis's shorter dictionary for students: the same scholarship in plain, modern definitions.

potissimum (-sumum) adv. sup.
potis, chiefly, principally, especially, eminently, above all : Quem vocabo ad cenam Potissimum? T.: exsistat aliquis et potissimum Caecus ille: te potissimum hoc persequi oporteret: quid agam? aut quo potissimum infelix accedam? S.

Origins

Adverbial accusative of potissimus.

Quick answers

What does potissimum mean in Latin?
potissimum, a adverb, means “chiefly, above all”.
How do you pronounce potissimum?
In classical Latin, [pɔˈtɪs.sɪ.mũː]; in ecclesiastical (church) Latin, [poˈtis.si.mum].