A non-commissioned officer (NCO) labels those in the armed services who have powers of command over their fellows, but are not trained as officers - in the British services, they do not 'hold the Queen's commission', which is the mark of "an officer and a gentleman".
- The two terms are held to be necessarily synonymous, in the military, in a clear marking of traditional patterns of recruitment. 'Officers' ("gentlemen") were members of the educated classes, born and brought up to the idea of command, and endowed (until after the Crimean War (1853-1856) showed the failings of the system) with enough money to buy themselves a commission - in extreme cases, to raise a regiment which they could then command. Other Ranks (OR) were the ordinary ('private') soldiers who were subject to the commands of the officers. (In the US services, they are known as enlisted men. They were drawn from the uneducated classes, and tended to join the services for more desperate motives usually money, sometimes starvation; and even as a preferable alternative to jail. The echoes of these class distinctions continue to reverberate: in barracks, officers eat in an Officers' Mess, where formal dinners are served by Other Ranks, with fine silver cutlery, elegant food and wines, and all is of the most formal polish; the men eat in self-service canteens, which resemble canteens anywhere else. It is these men whom the great Duke of Wellington called "the scum of the earth", remarking "I don't know what they do to the enemy, but by God, they frighten me!"
To deal with this frightening class, the services have since time immemorial appointed trustworthy members to act as intermediaries who would handle the direct tasks of habituating new recruits to military discipline, habits and practices. These are now recognized as Non-commissioned Officers. In the army, they include lance-corporal (the lowest NCO; a 'one-striper', i.e. having only one chevron sown to the sleeve); corporal (two-striper'); sergeant (three chevrons); Sergeant-Majors of different sorts (e.g. Company Sergeant-Major (CSM) and Regimental Sergeant-Major (RSM), a;long with certain other Warrant Officers). Different branches of the services use different nomenclature - the Royal Artillery refers to its 'Corporals' as Bombardiers, and the RAF calls its senior sergeants Flight Sergeants. The Royal Navy has a separate system to describe its NCOs.