Definition of "tunable"

Then doe all with a tunable voice of shouting bid him welcome.

1624, John Smith, Generall Historie, Kupperman, published 1988, pages 147–8

she rather chose to follow the Fortunes of a Wheel-Barrow, than those of a Distaff; daily, charming the Ears of the Publick with the Tuneable and Melodious Cry, of, Come who throws here? Who ventures for an ORANGE?

1723, Charles Walker, Memoirs of Sally Salisabury, section I

If you are working with TCP, some specific tunables are also available. By default, some TCP tunables have a value that is too low.

2013, Sander van Vugt, Red Hat Enterprise Linux 6 Administration: Real World Skills for Red Hat Administrators‎