Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
optābĭlis, e, adj. [opto], to be wished for, desirable (class.): quae expetenda atque optabilia videntur, Cic. de Or. 1, 51, 221: mihi pax imprimis fuit optabilis, id. Phil. 7, 3, 7: tempus, Ov. M. 9, 758: quae ut concurrant omnia, optabile est, Cic. Off. 1, 14, 33.
Comp.: bono viro optabilius, Cic. Pis. 14, 33.
Sup. seems not to occur.
Adv.: optābĭlĭter, desirably (post-class.).
Comp. optabilius, Val. Max. 5, 1, 6 ext.