Apilāpanatā (feminine) in the passage at Dhs 14 = Nidd II §628 is evidently meant to be taken as a + pilāpana + tā (from pilavati, plu), but whether the derivation and interpretation of As is correct, we are unable to say. On general principles it looks like popular etymology Mrs. Rh.D. translates (p. 16) "opposite of superficiality" (lit "not floating"); see her detailed note BMPE 14 note 3.
(fem, fem) state of non-drifting (in definition of sati)