Definition

1. Adjective:

   • Being one more than seventeen: The number that follows seventeen and precedes nineteen in the natural number sequence. It is represented by the numeral 18.

2. Noun:

   • The cardinal number that is the sum of seventeen and one: The number 18. It can represent a quantity, an age, or a position in a sequence.

Examples of Usage

• Adjective:
  • She has eighteen books on the shelf.
  • The recipe calls for eighteen eggs.
• Noun:
  • The number written on the door was eighteen.
  • He celebrated his eighteenth birthday last week. (Note: Here, 'eighteen' is used attributively to form the ordinal number 'eighteenth'.)

Advanced Usage

• "Sweet eighteen": A phrase sometimes used to refer to a person's 18th birthday, marking the transition to legal adulthood in many countries.
  • She is looking forward to her sweet eighteen.
• "Eighteen-hole course": A standard full-size golf course.
  • We played a round on an eighteen-hole course. (Note: This is a compound adjective; the core meaning of 'eighteen' as a quantity is retained.)

Variants and Related Words

• Eighteenth (adj, n): Constituting number eighteen in a sequence; the ordinal form of eighteen.
  • This is the eighteenth edition of the book.
• Eighteenfold (adv, adj): By a factor of eighteen; eighteen times as much.
  • The value increased eighteenfold.
• Eighteen-wheeler (n): A large truck with eighteen wheels (a compound noun).
  • The highway was busy with eighteen-wheelers.

Synonyms

• XVIII: The Roman numeral for eighteen.
• A score minus two: An archaic or poetic way to refer to the number (a score is twenty).

Related Phrases

• To be eighteen (years old): To have reached the age of eighteen.
  • In this state, you can vote if you are eighteen.
• Under eighteen: Younger than eighteen years of age.
  • The film is rated R, so no one under eighteen is admitted.

Related Idioms

• Eighteen to the dozen: Very rapidly or incessantly (a less common variant of the idiom "nineteen to the dozen").
  • She was talking eighteen to the dozen about her trip.

Adjective

1. being one more than seventeen

Noun

1. the cardinal number that is the sum of seventeen and one