| LA | Los Angeles; Library Association; Literate in Arts; Liverpool Academy; Louisiana |
| LAA | Light Anti-Aircraft |
| Lab | Labour |
| LAC | London Athletic Club |
| LAMDA | London Academy of Music and Dramatic Art |
| Lancs | Lancashire |
| LAPADA | London and Provincial Antique Dealers' Association |
| LC | Cross of Leo |
| LCC | London County Council (later GLC) |
| LCP | Licentiate, College of Preceptors |
| LD | Liberal and Democratic; Licentiate in Divinity |
| Ld Lt | Lord-Lieutenant |
| Ldr | Leader |
| LDS | Licentiate in Dental Surgery |
| LDV | Local Defence Volunteers |
| Ldy | Lady (e.g., -in-Waiting) |
| LEA | Local Education Authority |
| Leics | Leicestershire |
| LG | Lady Companion, Order of the Garter |
| LGSM | Licentiate, Guildhall School of Music and Drama |
| LGStJ | Lady of Grace, Order of St John of Jerusalem |
| LH | Light Horse |
| LHD | Literarum Humaniorum Doctor (Doctor of Literature) |
| LI | Light Infantry; Long Island |
| Lib | Liberal |
| Lib Dem | Liberal Democrat |
| Lic | Licence |
| LIFFE | London International Financial Futures and Options Exchange |
| Lincs | Lincolnshire |
| Lit | Literary |
| Lit Hum | Literae Humaniores (Classics) |
| LittD | Doctor of Literature; Doctor of Letters |
| LLA | Lady Literate in Arts |
| LLB | Bachelor of Laws |
| LLC | Limited Liability Company |
| LLCM | Licentiate, London College of Music |
| LLD | Doctor of Laws |
| LLM | Master of Laws |
| LM | Licentiate in Midwifery |
| LMCC | Licentiate, Medical Council of Canada |
| LMH | Lady Margaret Hall, Oxford |
| LMS | London, Midland and Scottish Railway; London Missionary Society |
| LMSR | London Midland and Scottish Railway |
| LMSSA | Licentiate in Medicine and Surgery, Society of Apothecaries |
| LNER | London and North Eastern Railway |
| LNWR | London and North West Railway |
| LP | Life Peer; Limited Partnership |
| LPTB | London Passenger Transport Board |
| LRAM | Licentiate, Royal Academy of Music |
| LRB | London Rifle Brigade |
| LRCP | Licentiate, Royal College of Physicians, London |
| LRCPE | Licentiate, Royal College of Physicians, Edinburgh |
| LRCPI | Licentiate, Royal College of Physicians of Ireland |
| LRCS | Licentiate, Royal College of Surgeons of England |
| LRCSE | Licentiate, Royal College of Surgeons, Edinburgh |
| LRCSI | Licentiate, Royal College of Surgeons in Ireland |
| LRIBA | Licentiate, Royal Institute of British Architects |
| LRPS | Licentiate, Royal Photographic Society |
| LSA | Licentiate, Society of Apothecaries; Licence in Agricultural Sciences |
| LSE | London School of Economics and Political Science |
| LSO | London Symphony Orchestra |
| LSWR | London and South-Western Railway |
| LT | London Transport; Licentiate in Teaching |
| LTA | Lawn Tennis Association |
| LTB | London Transport Board |
| LTCL | Licentiate, Trinity College of Music, London |
| Ltcy | Lieutenancy |
| Ltd | Limited |
| LTE | London Transport Executive |
| LTh | Licentiate in Theology |
| LVO | Lieutenant, Royal Victorian Order (formerly MVO (Fourth Class)) |