A very short written way of saying 'thanks'. You use it in text messages, chat apps, and quick emails between friends or close colleagues — never in a letter, a report, or a message to a teacher, a customer, or a boss you do not know well. It is not really a word you say out loud; if you read it aloud you just say 'thanks'. It belongs to the same family of typing shortcuts as 'pls' (please), 'ur' (your/you're) and 'ttyl' (talk to you later), and like them it can be written with small letters too: thx. People often stretch it for warmth — 'thx!!', 'thx so much' — because bare 'thx' can read as a little cold or rushed, the way a one-word reply does. Two things to know: 'THX' in capital letters is also a famous cinema sound company, so on a film poster or a speaker it means something completely different; and in a work chat, whether 'thx' feels friendly or lazy depends entirely on the office, so watch what other people write before you use it.