Squire was a title given to either a knight's servant or a village leader.
Warlord Yago called his followers his "squires." (TOS comic: "Child's Play")
Trelane styled himself the "Squire of Gothos." (TOS episode: "The Squire of Gothos", TNG novel: Q-Squared)
Vincent Wexler gave Mackenzie Calhoun the nickname of "squire" when they first met at Starfleet Academy. (NF novel: Stone and Anvil)
In the holodeck program Reginald Barclay wrote for Worf in 2369, he cast himself as Worf's squire. (TNG novel: Here There Be Dragons)