A number of stories are circulating about the etymology of Souillac, although the most heard is that Souillac, in Occitan ‘Solhac’, is originally Gallo-Roman and refers to Solius, the original owner of the land. The suffix -ac comes from the gallic -acon (which in turn descends from the celtic) and stands for ‘the domain of’.
Another explanation is that the name Souillac comes from the local dialect word ‘la souilh’, which stands for a watering hole where wild boars gather. Which also explains why Souillac depicts a boar on its coat of arms.