Definition
The word for “luck” in German is Glück. However, the word glücklich does not usually mean “lucky”, for which there actually is no word in German (glücklich actually means “happy”, “satisfied” or “contented”). Rather, to express “to be lucky”, one would have to say Glück haben — “to have luck”.
Examples
Er hatte Glück. He was lucky.
Herzlichen Glückwunsch. Congratulations” (literally “hearty luck-wish”)
Zum Glück. Fortunately.
Viel Glück! Good luck!
Glücklicher Zufall — Fortunate coincidence
Glücksbringer — Lucky charm
Glückssträhne — Streak of good luck
Good to Know
More idiomatically, Schwein haben (literally “to have a pig”) can also be used to express ‘having a stroke of luck‘.
The opposite of Glück is Pech.