From The Collaborative International Dictionary of English v.0.48 [gcide]:
Placable \Pla"ca*ble\, a. [L. placabilis, fr. placare to quiet,
pacify: cf. F. placable. See Placate.]
Capable of being appeased or pacified; ready or willing to be
pacified; willing to forgive or condone.
[1913 Webster]
Methought I saw him placable and mild. --Milton.
[1913 Webster]
From WordNet (r) 3.0 (2006) [wn]:
placable
adj 1: easily calmed or pacified [ant: implacable]