The headword -- presumably extracted from the quotation given, its only independent attestation -- is the aorist active participle, masculine accusative singular, of the verb parei/rw.
[1] Polybius 18.18.13 (web address 1), detailing the construction of Roman palisades and favorably contrasting them with those built by the Greeks. The branches were harvested and carried, but not trimmed to a simple stake; for a palisade, the few remaining branchlets were woven into a resilient meshwork (Walbank, pp. 573-4).