B1
not having something, or not having enough of something
Dictionary examples:
His lack of direction skills turned a short walk into an adventure. (0.0)
Due to lack of height, he used a trampoline to kiss his girlfriend. (0.0)
His lack of dating experience made every girl seem like a mystery. (0.0)
a lack of money (11.4)
She certainly has no lack of friends. (16.3)
If he fails it won't be through lack of effort. (25.6)
Your problem is lack of confidence. (35.9)
Lack of sleep had made him irritable. (53.1)