- 2B1Q (2 Binary 1 Quaternary)
- 2CMBA (2nd Chemical Mortar Battalion Association)
- 2CTVHA (2nd Connecticut Volunteer Heavy Artillery)
- 2CVF (Two Chamber Vacuum Furnace)
- 2D (two-dimensional (geophysics))
- 2-D (Two-Dimensional)
- 2dF ((instrumentation) Two-degree Field, spectrograph on the Anglo-Australian Telescope)
- 2dFGRS ((observing program) Two-degree-Field Galaxy Redshift Survey)
- 2d Lt (Second Lieutenant)
- 2E (Role 2 Enhanced)
- 2FG (Two-point field goal. Used in Euroleague Basketball box scores, but not generally in North America.)
- 2GACL (2nd Georgia Battalion of the Continental Line)
- 2GL (Second-Generation Programming Language)
- 2IC (Second In Command)
- 2IDKWVA (2nd Infantry Division Korean War Veterans Association)
- 2KYOB (2nd Regiment Kentucky Infantry Orphan Brigade)
- 2LM (Role 2 Light Maneuver)
- 2LT (Second Lieutenant)
- 2M (Micro Miniature)
- 2MASP ((catalog) Two-Micron All Sky Survey Prototype, an early version of the 2MASS catalog)
- 2MASS ((observing program/catalog) Two-Micron All Sky Survey, an all-sky survey in the near-infrared; also, the catalog of sources from the survey)
- 2MASSI ((catalog) Two-Micron All Sky Survey, Incremental release, one of the versions of the 2MASS catalog)
- 2MASSW ((catalog) Two-Micron All Sky Survey, Working database, one of the versions of the 2MASS catalog)
- 2MNLA (2nd Minnesota Battery Light Artillery)
- 2MRLBI (Colonel Bailey's 2nd Massachusetts Regiment Lear Brigade of Infantry)
- 2NF (Second Normal Form)
- 2NJCL (2nd New Jersey Regiment of the Continental Line)
- 2NT (Bridge bid to take 8 tricks, No Trump)
- 2P (proved and probable reserves)
- 2RIVI-B (Company B Second Regiment Rhode Island Volunteer Infantry)
- 2S2D (Double Sided Double Density)
- 2SLAQ ((observing program) 2dF-SDSS LRG And QSO survey)
- 2W (Two Wire)
- 2 WVI (2nd West Virginia Infantry Regiment)
- 2WVIA (2nd Wisconsin Volunteer Infantry Association)