harden
/ˈhɑːdn ˈहाड्न्/ verb 1 [I, T] to become or to make something hard or less likely to change सख़्त बनना या बनाना कि उसमें कोई परिवर्तन न हो सके
The concrete will harden in 24 hours.
The firm has hardened its attitude on this question.