How to Say "battle ally" in Greek

The word σύμμαχος is technically an adjective of sorts (cf. LSJ Greek-English Lexicon) meaning "allied with" someone in battle. But at times, I have used it as a substantive with the meaning "battle ally," a usage that appears in ancient Greek literature (s.v. LSJ). The plural substantival nominative form is οἱ σύμμαχοι.
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