Definition of triple nine:
(n) :
Alternative form of 999 (“telephone number for emergency services in many jurisdictions”). [The telephone number for emergency services in the United Kingdom, Ireland, Hong Kong, Macau, Malaysia, Bangladesh, Burma, Bahrain, Qatar, the UAE, Kenya, Uganda, Zambia, Zimbabwe, Ghana, Sudan, South Sudan, Sierra Leone, Guyana, Antigua and Barbuda, Saint Lucia, Saint Vincent, Dominica, Kiribati, Samoa, the Solomon Islands, and the Seychelles.]