a series of waves in the hair made by applying heat and chemicals
"She spent an hour at the salon getting her curly perm, which gave her hair those perfect bouncy waves."
A permanent.
"The programmer spent hours debugging a complex algorithm that relied on generating every possible perm of the input array to find an optimal solution."
A permutation.
To give hair a perm, using heat, chemicals etc.
"She decided to get a perm at the salon to add some volume and curls to her straight hair."
A historical region of northeastern Russia, corresponding to the Kama basin, a left tributary of the Volga.
"The historian corrected her notes to specify that the ancient Perms were located along the Kama river in northeastern Russia rather than near modern-day Perm city."