We propose a generalization of Sahlqvist formulae
to polyadic modal languages by representing modal polyadic languages in a
combinatorial style and thus, in particular, developing what we believe to
be the right approach to Sahlqvist formulae at all. The class of polyadic
Sahlqvist formulae PSF defined here expands essentially the so far known
one. We prove first-order definability and canonicity for the class PSF.