The headword is attested only in lexicography, grammars and scholia (e.g. Herodian 3.1.113). A scholium to Aristophanes, Lysistrata 988 (web address 1), comments on a version of the text that contains the headword, although the OCT reads palaio/r, a Laconian variant for palaio/s ('ancient'). The scholiast explains the headword as being a variant of a)leo/s (Doric/Laconian for h)leo/s), defined in LSJ as "distraught, crazed" (web address 2) but understood by the scholiast as "silly, useless". Henderson (below), among others, prints a)leo/s.
[1] Almost = Etymologicum Gudianum s.v. palaio/s, where the current headword is accented differently (pa/leos) and has the order of the glosses reversed. See also Theognostus, Canones 270.