Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
plācābĭlĭtas, ātis, f. [placabilis], readiness to be appeased, placable disposition, placability: nihil magno et praeclaro viro dignius placabilitate atque clementiā, Cic. Off. 1, 25, 88.