IPA: //ˈædʒʊtənt//
KK: /ˈædʒʊtənt/
A person who assists a commanding officer, especially in military settings, by handling administrative tasks and correspondence.
The adjutant prepared the necessary documents for the upcoming mission.
Adjutant is derived from the Latin "adjutare" (meaning to help) which is a frequentative form of "juvare" (meaning to aid or assist). The word combines "ad-" (meaning to) and "juvare" (meaning to help). An adjutant is therefore someone who helps or assists, particularly in a military context.
Think of someone who is 'helping' ('adjutare') in a supportive role — that's what an adjutant does.