attendant; member of an entourage
Refers to a person who accompanies someone, often in a formal or official capacity, such as a member of a retinue, party, or delegation.
I attended the meeting as a member of the president's entourage.
彼は大使の随伴者として海外に派遣された。
He was dispatched overseas as an attendant to the ambassador.
随行員 is similar but often used for members of an official traveling party, such as a diplomatic mission. 随伴者 can be used in broader contexts.
Compound of 随伴 (zuihan, 'accompanying') + 者 (sha, 'person'). The exact historical derivation is uncertain, but the spelling is conventionally associated with the meaning of a person who accompanies another.