To sour or curdle.
Sour or curdled milk.
Wet clay or mud.
To unpalatalize or velarize.
To become or make (a person or thing) resistant or less sensitive.
To become or make (a consonant) more fortis; to (cause to) undergo fortition.
To strengthen.
To make something hard or harder (tough, resistant to pressure).
To modify (a website or other system) to make it resistant to malicious attacks.
To become hard (tough, resistant to pressure).