| T | Telephone; Territorial |
| T&AFA | Territorial and Auxiliary Forces Association |
| T&AVR | Territorial and Army Volunteer Reserve |
| T/ | Temporary rank, e.g., T/Capt (Temporary Captain) |
| TA | Territorial Army; Telegraphic Address |
| TAA | Territorial Army Association |
| TAR | Territorial Army Reserve |
| TARO | Territorial Army Reserve of Officers |
| TAS | Torpedo and Anti Submarine Course |
| TASS | Technical, Administrative and Supervisory of AUEW |
| Tbnl | Tribunal |
| TCD | Trinity College, Dublin (University of Dublin, Trinity College) |
| TCF | Temporary Chaplain to the Forces |
| TD | Territorial Decoration; Territorial Efficiency Decoration; Efficiency Decoration (T&AVR) (from April 1967); Teachta Dala (Member of the Dail, Eire) |
| TEC | Technician Education Council; Training and Enterprise Council |
| Tech | Technical |
| TEFL | Teaching English as a Foreign Language |
| TEM | Territorial Efficiency Medal |
| Temp | in the time of; temporary |
| Tenn | Tennessee |
| TF | Territorial Force |
| TFA | Territorial Forces Association |
| TFR | Territorial Force Reserve |
| TGWU | Transport and General Workers' Union |
| ThL | Theological Licentiate |
| TM | Their Majesties |
| TN | Tennessee |
| TP | Transvaal Province |
| Tport | Transport |
| Trans/trans | Transferred; Translation; Translated |
| Transf | Transferred |
| Treas | Treasurer |
| Trg | Training |
| TRH | Their Royal Highnesses |
| Trin | Trinity |
| TS | Training Ship |
| TSB | Trustee Savings Bank |
| Tst | Trust |
| tstee | trustee |
| Tstte | Trustee |
| TUC | Trades Union Congress |
| TUS | Trade Union Side |
| TV | Television |
| TX | Texas |