Definition

1. Cardinal Number:

   • The number equivalent to the product of ten and nine; 90.
   • A symbol representing this number, such as 90 or XC.

2. Noun (plural: nineties):

   • The decade from 90 to 99 in a century, especially the twentieth century (the 1990s).
   • The range of temperature, age, or other measurement from 90 to 99.

3. Adjective:

   • Amounting to ninety in number.

Usage Examples

• As a Cardinal Number:

  • The book has ninety pages.
  • Ninety percent of the students passed the exam.

• As a Noun (The Nineties):

  • My parents were born in the nineties. (This typically refers to the 1990s.)
  • Temperatures are expected to be in the nineties this weekend. (Meaning between 90-99 degrees Fahrenheit.)

• As an Adjective:

  • She is ninety years old.
  • I need ninety copies of this document.

Advanced Usage

• "Ninety-nine times out of a hundred": An idiom meaning "almost always" or "very frequently."

  • Ninety-nine times out of a hundred, this method works perfectly.

• "The Gay Nineties": A historical term referring to the 1890s, often characterized as a period of prosperity and cultural change.

Variants and Related Words

• Ninetieth (adj. & n.): Constituting number ninety in a sequence; position 90.
  • This is her ninetieth birthday.
• Ninety-one, ninety-two, etc.: The numbers following ninety (91, 92, etc.).

Synonyms

• Four score and ten: An archaic term for ninety.
• XC: The Roman numeral for ninety.

Related Phrases

• In one's nineties: Being between 90 and 99 years of age.
  • My grandmother is in her nineties and still very active.

Idioms

• Ninety-nine times out of a hundred: Almost invariably.
  • He's late ninety-nine times out of a hundred.
• Ninety-day wonder: (Informal, sometimes derogatory) A person who has received a rapid, short-term commission or training, especially in the military.

Adjective

1. being ten more than eighty

Noun

1. the cardinal number that is the product of ten and nine