Field officer. (n.d.). In YourDictionary. Retrieved from https://www.yourdictionary.com/field-officer
(plural field officers)
A (para)military commissioned officer who holds a field grade, ranking under general officers but above lower grades and fit to command medium-size units on the field, such as a battalion or regiment; or a non-army equivalents in rank.
English Wiktionary. Available under CC-BY-SA license.