Definition of "deadening"

Until, of course, the war and its aftermath came to lay their deadening hand on all railway progress.

1948 January and February, Cecil J. Allen, “British Locomotive Practice and Performance”, in Railway Magazine, page 48

The structural theory doesn't only focus on the negations, repressions, disavowals, and deadenings of the ego in the face of its encounters within and without.

2012, Daniel Sapen, Freud's Lost Chord: Discovering Jazz in the Resonant Psyche, page 38