An attendant was an individual who attends others or another in performing a service.
Prior to the departure of the USS Enterprise from the planet Mudd in 2268, Captain James T. Kirk had a special android programmed as an attendant for Harry Mudd, who was to remain on the planet, designed to take care of his every need. He described the attendant as someone who would "help you find an incentive to work with the androids and not exploit them." Mudd thought the gesture was "unexpectedly civil" of Kirk, until he discovered the attendant in question was five hundred android replica of his wife, Stella. (TOS: "I, Mudd")
According to Syrus, William T. Riker, who was a patient in the Tilonus Institute for Mental Disorders, had allegedly tried to escaped and after he had struggled with one of the attendants, he had hit his head on a door. (TNG: "Frame of Mind")
When Drayans prepare for their deaths, individuals were taken to an outer moon of their system, where while being cared for and protected by attendants. These attendants typically helped the elderly prepare to take the final step into the unknown. (VOY: "Innocence")