ejercicio
/exeɾˈθiθjo/ · B1 · noun · m
exercise
🏋️ Spanish j stands in for x: exercise → ejercicio, kin of ejército (army)
From Latin exercitium, training, the same root as ejército, an army that drills. Old Spanish exercicio became ejercicio when the x sound turned into j. It also means holding a post (en ejercicio = in office) and a fiscal year (ejercicio fiscal).