The Full Form of JCO and OR is‍ Junior Commissioned Officer and Other Rank.

Junior Commissioned Officer (JCO) is a term used for a group of military personnel which is higher than havildars and lower than lieutenants; this term is only used by India and Pakistan. Senior havildars are promoted to JCO rank on the basis of merit and seniority, restricted by the number of vacancies. JCOs are treated as a separate class and hold many privileges. With good pay and privileges, it is an ambition of most enlisted men to attain such rank. Primarily the term was associated with armies but since 2000s India and Pakistan’s navies and forces are using the term to indicate their Chief Petty Officers and Warrant Officers. The British Indian Army recruited Gurkha soldiers from Nepal since the 19th century and separate Gurkha Regiments were created for them, the Gurkha soldiers got same ranks as other Indian soldiers; the modern Nepal Army officially made the Indian Army rank system for their soldiers in 1960s through a series of reorganizations and the ‘JCO’ term is being used by them from then. After the secession of East Pakistan in 1971 the Bangladesh Army inherited the ‘JCO’ rank system from Pakistan Army though since early 2000s the army uses the Warrant Officer terms.