field-grade officer(n = noun.person) field officer, fo - an officer holding the rank of major or lieutenant colonel or colonel;
is a kind of commissioned military officer

action officer, air force officer, army officer, case officer, chief executive officer, chief financial officer, chief operating officer, chief petty officer, church officer, commanding officer, commissioned military officer, commissioned naval officer, commissioned officer, desk officer, disinfestation officer, executive officer, field officer, financial officer, flag officer, general officer, hearing officer, intelligence officer, law officer, line officer, medical officer, military officer, naval officer, noncommissioned officer, officer, peace officer, petty officer, police officer, presiding officer, probation officer, prosecuting officer, returning officer, ship's officer, staff officer, supply officer, warrant officer