The term 'causing to lose hope' can be summed up in one word: demoralising. This term is used to describe an action or event that has a negative effect on someone's morale, making them feel hopeless and disheartened. It is often used in the context of military operations, where a demoralising attack can have a devastating effect on the enemy's will to fight. It can also be used in other contexts, such as in the workplace, where a demoralising comment or action can have a detrimental effect on an employee's motivation.