noun, masculine/pu/plural: poux
louse; head louse (Pediculus humanus capitis)
Related: chercher des poux, être dans les poux de bois, laid comme un pou, pouilleux
Inherited from Old French pouil, peouil, püil, from Late Latin peduclus < peduculus, variant of Latin pēdīculus, from pēdis, from Proto-Indo-European *pezd-. The singular is a back-formation from the plural (see also genou with the same development).