toughness russian

• жёсткость

  stiffness, rigidity, hardness

  harshness, severity, toughness

  hardness (of water)

• выно́сливость

  endurance, stamina, staying power, fortitude

  hardiness, toughness, resistance

  resilience, frustration tolerance

• зака́лка

  tempering, hardening, training, acquired toughness

• вя́зкость

  viscosity

  toughness, tenacity

• кре́пкость

  strength, firmness, sturdiness

  hardness, toughness