Meaning

noun an officer who acts as military assistant to a more senior officer

noun large Indian stork with a military gait

originProbably partly from Spanish ayudante and partly Portuguese ajudante (“assistant, helper, aide”), use as nouns of adjectives from the present participles of Spanish ayudar and Portuguese ajudar, respectively, from Latin adiūtō (“to help, assist”), with remodeling after Latin adiūtāns, present participle of adiūtō, from adiuvō (“to help, assist”) + -tō (frequentative suffix).

Etymology from Wiktionary, CC BY-SA 3.0