MO
Abbreviation with 5 meanings
| Stands for | Missouri |
|---|---|
| Meanings | 5 |
| Categories | Geography & Places, Writing & Everyday, Units & Measurements, Science & Engineering |
| Also written | M.O., Mo, mo |
MO has five meanings. The most common are Missouri (US state) and Modus operandi (method of operating) (Latin); it can also stand for Month, Macao and Molybdenum.
Meanings of MO at a glance
| # | MO stands for | Context |
|---|---|---|
| 1 | Missouri | Geography & Places › US State |
| 2 | Modus operandi (method of operating) | Writing & Everyday › Latin |
| 3 | Month | Units & Measurements › Time |
| 4 | Macao | Geography & Places › Country Code |
| 5 | Molybdenum | Science & Engineering › Chemical Element |
1. Missouri
Geography & Places · US State Abbreviations
The Show-Me State in the central US, admitted on August 10, 1821, as the 24th state under the Missouri Compromise. Jefferson City is the capital, Kansas City and St. Louis are the largest cities, and Missouri borders eight other states, tied with Tennessee for the most.
Example: Our Springfield, MO distribution center handles all Midwest returns.
Traditional and AP abbreviation: Mo., which shares the code's letters and appears in AP datelines such as JOPLIN, Mo. The code was assigned in 1963; MI, MS and MT are the usual mix-ups, and Montana is MT, not MO. MO also means modus operandi and mail order, and it is the ISO country code for Macao.
2. Modus operandi (method of operating) (M.O.)
Writing & Everyday · Latin Abbreviations · also used in government
Describes a person's or group's characteristic way of doing something, especially a criminal's recognizable pattern of behavior. Police and crime writers use it to link offenses, and general speakers use it for any habitual approach.
Example: Detectives noticed the same M.O. in all three burglaries: rear windows forced with a flat screwdriver.
The plural is modi operandi. Criminologists distinguish the M.O., which can change as an offender learns, from a "signature," behavior that serves a personal need and stays constant across crimes. In casual use it is often written MO without periods. The related phrase modus vivendi means a working arrangement that lets opposing parties coexist.
3. Month (mo)
Units & Measurements · Time Abbreviations
Used in prices, subscriptions, ages of babies and contract terms: $15/mo, a 6-mo-old, a 24-mo lease. Calendar months run from 28 to 31 days, so "per mo" means per calendar month rather than per 30 days.
Example: Unlimited plan, $45/mo with autopay, no annual contract.
Medical notes record infant ages as "9 mo" or "9 mos", mos being the usual plural. The average Gregorian month is 30.44 days, which matters when converting monthly rates to daily ones. Do not confuse mos with MOS, the military occupational specialty, or with M.O., modus operandi.
4. Macao
Geography & Places · Country Code Abbreviations
Special Administrative Region of China since December 20, 1999, after more than four centuries of Portuguese administration. Macao is the world's largest gambling center by revenue, has its own currency, the pataca (MOP), and its alpha-3 code is MAC.
Example: Casino revenue in MO rebounded strongly after travel restrictions ended.
Macao is also spelled Macau; ISO uses Macao. In US addresses MO is Missouri, and MO also means modus operandi. Portuguese remains an official language alongside Chinese.
5. Molybdenum (Mo)
Science & Engineering · Chemical Element Abbreviations
With a melting point of about 2,623 °C, molybdenum (element 42) is alloyed into high-strength steels for tools, pipelines and engine parts. Molybdenum disulfide is a dry lubricant for heavy machinery, and the metal is a cofactor in nitrogenase, the enzyme bacteria use to fix atmospheric nitrogen.
Example: The bike's 4130 chromoly tubing is a steel containing about 0.2% Mo.
Carl Wilhelm Scheele showed in 1778 that the mineral molybdenite was neither lead ore nor graphite, and Peter Jacob Hjelm isolated the metal in 1781. The name comes from Greek molybdos (lead), reflecting the old confusion between soft, dark lead minerals and molybdenite. Engineers and mechanics often shorten the metal to "moly," as in moly grease.
Related abbreviations
More US state abbreviations
- MD – Maryland
- ME – Maine
- MI – Michigan
- MN – Minnesota
- MS – Mississippi
- MT – Montana
- NC – North Carolina
- ND – North Dakota
See all 51 US state abbreviations →