Or "nous" in French, or "noi" in Italian or "nós" in Portuguese. :)
Since a good chunk of Esperanto comes mostly from the Romance languages, I would not be surprised if this is no coincidence. Just like "vi" starts with the same letter as "vosotros" in Spanish, "vous" in French, "voi" in Italian, and "você" in Portuguese.
Repeat of a post way up there somewhere: My Esperanto dictionary (Wells) gives Vortgrupo for the English phrase. Frazo can be used to mean a musical phrase though.
Let me add that Cseh's Konversacia vortaro says: Frazo = vortoj inter granda litero kaj punkto.
In conclusion: Frazo means sentence. That's why "phrases" was wrong.
I do not have the O'Connor dictionary. I do have the Benson, the Wells (2 different), the Cherpillod, the Nixon, the Cseh, and the PIV (2 of them, different eras as well as a PV) as well as a number of fakvortaroj (which I did not consult, since the Ĥemia vortaro and the various other scientific and engineering dictionaries don't dwell much on grammar) and only one (Nelson) includes phrase as a translation of Frazo. I also checked my electronic dictionaries; Lernu.net, Sonja's dictionary, la Rata vortaro, and all of the apps on my iPad all said "frazo= sentence" though La Rata suggested that "phrase" may also translate to frazo. Only the Vikipedia supports you, and we all know about how accurate any of the wikis can be (not).
This is why we studied the sentence earlier about Esperantists having large dictionaries.