crisis
Entry from World dictionary
Pronunciation:/ˈkrʌɪsɪs/
noun (plural crises /-siːz/)
- a time of intense difficulty or danger:the current economic crisis [mass noun] :the monarchy was in crisis
- a time when a difficult or important decision must be made:[as modifier] :the situation has reached crisis point
- the turning point of a disease when an important change takes place, indicating either recovery or death

Origin:
late Middle English (denoting the turning point of a disease): medical Latin, from Greek krisis 'decision', from krinein 'decide'. The general sense ‘decisive point’ dates from the early 17th century

Spelling rule
Make the plural by changing the - is ending to -es: (crises ).
Meaning
Subject
Click any link to see words in that category