Lucky means good things happen to you by chance, not because you earned them. The parking space right outside the door, the one dry hour in a wet week, the exam question you happened to revise the night before.
It attaches to objects and events as well as people: a lucky number, a lucky shirt, a lucky escape, a lucky break. Fortunate means much the same but sounds like a form; lucky is what you actually say out loud. Two frames to keep straight: you are lucky TO have something, and you are lucky THAT something happened. Sarcasm has taken over parts of the word — lucky you and lucky me are said flat, and in Britain you will be lucky means it is not going to happen. Get lucky can mean a good result or sex, so read the room first.
1adjectiveluckyHaving good things happen to you by chance.
“You were lucky the shop was still open at that hour.”
synonyms: fortunate
2adjectivecharmBelieved to bring good luck.
“He wore his lucky socks to every match that season.”
3adjectiveevent(of an event) Happening by good chance.
“It was a lucky escape — the branch missed the car by inches.”
Too few real examples of this word to estimate which sense is commonest.
Also accepted in games: fortunate
Lucky is luck plus -y, written down in Middle English as lukky. The relatives are all Germanic — Dutch gelukkig, German glucklich — but in those languages the word drifted towards happy, while English kept it pointed at chance.
Middle English
lukky
English, today
lucky
From Middle English lukky, equivalent to luck + -y. Cognate with Scots lucky (“lucky”), West Frisian lokkich (“lucky, fortunate”), Dutch gelukkig (“lucky, fortunate, happy”). Compare also Danish lykkelig (“happy”), Swedish lycklig (“happy, lucky”), German glücklich (“happy”), stq glukkelk (“happy”).
Etymology from Wiktionary, CC BY-SA