To judge by the gloss, the headword -- a present participle in the nominative feminine singular -- is a dictation error for e)pilli/zousa, which would have been homophonous in the Suda's time (it is spelled thus in the derivative entry of ps.-Zonaras 840, and cf. epsilon 2447). It could also conceivably be a metrically lengthened form of e)pilu/zw ('hiccup at'). A similarly-formed participle e)pillu/zwn occurs at Nicander, Alexipharmaca 81. As for e)pilli/zousa, it is attested outside lexicography only at Nicander, Theriaca 163 (in reference to a snake). Only the second gloss would be appropriate for that context, however.
cf. Hesychius epsilon4936, where the same form is glossed with a different synonym for 'mocking'.
The Suda is the only source to connect this word with owls.