This is the 955th most frequent Turkish word.
yıldırım
"Yıldırım" means "lightning" in English.
Here, 'yıldırım' is used to describe the natural phenomenon of lightning.
Yıldırım gökyüzünde parladı.
The lightning flashed in the sky.
In this context, 'yıldırım' is used metaphorically to describe speed as being as fast as lightning.
Yıldırım hızıyla koştu.
He ran at lightning speed.
Here, 'yıldırım' is part of a historical figure's title, referring to Sultan Bayezid I, called 'Yıldırım' which means 'lightning'.