Acronyms are made by taking the first letter of each word. They are often used in text and online messaging, marketing and branding, and in situations in which phrases are often repeated.

messaging

brb – be right back
lol – laugh out loud (= that was funny)
lmao – laughing my ass off (= that was very funny)
roflmao – rolling on the floor laughing my ass off (= that was hilarious)
ttyl – talk to you later
fyi – for your information
fya – for your amusement

imo – in my opinion
imho – in my honest opinion

invitations

rsvp – repondez s’il vous plait (French for ‘please reply’)
byob – bring your own bottle (on party invitations, or at restaurants = bring whatever you want to drink)
asap – as soon as possible

military

AWOL – absent without leave (= they have left, but they shouldn’t have)
MIA – missing in action (= they went to do something, and haven’t come back)

leisure

DIY – do it yourself
CD – compact disc
DVD – digital video disc (or digital versatile disc)

crime

DUI – driving under the influence (= drunk driving, or driving whilst on drugs)

medical

AA – Alcoholics Anonymous (a group that helps people with drinking problems)
ADD – Attention Deficit (hyperactivity) Disorder (a problem of not being able to stay still or concentrate for long)
AIDS – Acquired Immune Deficiency Syndrome (later stage of HIV)
HIV – Human Immunodeficiency Virus
SARS – Severe Acute Respiratory Syndrome

ER – emergency room
OR – operating room

organizations

NGO – non-governmental organization

UN – United Nations
EU – European Union
NATO – North Atlantic Treaty Organization
WHO – World Health Organization
WTO – World Trade Organization

FIFA – Fédération Internationale de Football Association (French; English = International Federation of Association Football)

at work

CEO – Chief Executive Officer
CFO – Chief Financial Officer
PA – personal assistant

company names

QANTAS – Queensland and Northern Territories Air Service
BMW – Bayerische Motoren Werke (German; English = ‘Bavarian Motor Works’)

The website Acronym Finder can help you find the meaning to acronyms you don’t recognise or know.

Abbreviations are shortened versions of longer words.

etc. = etcetera (= and so on)

blog = web log

stat = statim (= immediately)

frat = fraternity (often used for drunk, stupid fraternities, rather than respected fraternities)

A comprehensive list of acronyms and abbreviations can be found at abbreviations.com

Chat Slang

Short messaging has its own language (terrible English, but useful to know)

cu = see you
ic = I see

cu l8r = see you later
gr8 = great

4 = for

2nite = tonight
2day = today
F2F = face-to-face

thx = thanks
xx = kisses
da = the
teh = the
b/c = because

143 = I love you (1 letter in ‘I’, 4 letters in ‘love’, 3 letters in ‘you’)
1432 = I love you too (2 = too)

FFS – for f***s sake

A longer list of chat slang can be found here