verb/a.ba.taʁ.diʁ/
to cause something's qualities or defining characteristics to degenerate; to defile or degrade; to bastardize; to degrade; to degenerate; to become bastardized
“1580, Michel de Montaigne, Essays, Book I, CHapter 26 (modernized spelling), translated by Charles Cotton” — Away with this violence! away with this compulsion! than which, I certainly believe nothing more dulls and degenerates a well-descended nature.
a- + bâtard (“bastard”) + -ir, originally "to bastardize, to make to lose racial characteristics"