Definition of "tamer"

Only Enid could dare him at such a time, and even she felt occasionally that sinking of the heart which the bravest of tamers may experience as he unbars the gate of the cage.

1925 July – 1926 May, A[rthur] Conan Doyle, “(please specify the chapter number)”, in The Land of Mist (eBook no. 0601351h.html), Australia: Project Gutenberg Australia, published April 2019