The Hebrew verb aphad (H640) means to gird on, to fasten, or to bind — specifically in the context of putting on or attaching the ephod. It is used twice in the Old Testament, both referring to the act of girding on the priestly ephod, the sacred vestment of the high priest.
The act of aphad — girding on the ephod — was an act of priestly investiture, a formal putting-on of sacred office. When David girded himself with a linen ephod to dance before the LORD (2 Samuel 6:14), he was enacting priestly symbolism, expressing that worship before God requires consecration. This models the New Testament teaching that all believers are a royal priesthood (1 Peter 2:9).