This ‘movement’ of Dasein in its own Being, we call its ‘downward plunge’ [Absturz]. Dasein plunges out of itself into itself, into the groundlessness and nullity of inauthentic everydayness.
Heidegger defines falling as Dasein’s constitutive ‘downward plunge’ into groundlessness and inauthenticity, concealed from itself by tranquillizing public interpretation.
, Being and Time, 1962thesis