Source : Webster's Revised Unabridged Dictionary (1913)

Companionable \Com*pan"ion*a*ble\, a.
   Fitted to be a companion; fit for good fellowship; agreeable;
   sociable. ``Each companionable guest.'' --Mallett.
   ``Companionable wit.'' --Clarendon. --
   {Com*pan"ion*a*ble*ness}, n. -- {Com*pan"ion*a*bly}, adv.

Source : WordNet®

companionableness
     n : suitability to be a companion [syn: {companionability}]