For the substance, see polyethylene oxide.

PEO stands for greek Παγκύπρια Εργατική Ομοσπονδία (Pancyprian Labour Federation).

It was instrumental in the 1948 strikes and has been closely related to AKEL.

When AKEL was declared illegal by the british colonial government of Cyprus, PEO and especially its leader Andreas Ziartides was the only legal leftwing political entity and it was expressing the politics underground AKEL.

PEO had a membership from all ethnic groups in Cyprus. In 1958 the turkish cypriot nationalistic organisation TMT launched a terror campaign against turkish cypriot members of PEO, killing the journalist Fazil Onder and attempting to kill the head of PEO's turkish bureau, Ahmet Sadi. Following those events, PEO's members were primarily greek cypriots.