5. defend= to protect someone or something from attack
e.g. Thousands of young men came forward, willing to defend their country.
e.g. defend someone/something from/against something: Steps are being taken to defend the city against attack.
e.g. defend yourself: You have a right to defend yourself if you are being attacked.
6. ecosystem= ① BIOLOGY all the plants and animals in a particular area, considered as a system with parts that depend on one another
② BUSINESS, COMPUTING all the different activities, companies, systems etc that are involved in a particular area of business, especially new technology
e.g. Today Apple’s iOS platform and ecosystem seem invincible.
TED Talks have become a mainstay of the online ecosystem.
7. invincible= too strong to be defeated
e.g. Teams like the Wallabies are not invincible.
