The Collaborative International Dictionary of English v.0.48:
Imaginable \Im*ag"i*na*ble\, a. [L. imaginabilis: cf. F. imaginable.] Capable of being imagined; conceivable. [1913 Webster] Men sunk into the greatest darkness imaginable. --Tillotson. -- Im*ag"i*na*ble*ness, n. -- Im*ag"i*na*bly, adv. [1913 Webster]