of

 
Pronunciation: /ɒv, (ə)v/

preposition

  • 1expressing the relationship between a part and a whole:
  • with the word denoting the part functioning as the head of the phrase: the sleeve of his coat in the back of the car the days of the week
  • after a number, quantifier, or partitive noun, with the word denoting the whole functioning as the head of the phrase: nine of the children came to the show a series of programmes [with mass noun]: a piece of cake
  • 2expressing the relationship between a scale or measure and a value: an increase of 5% a height of 10 metres
  • expressing an age: a boy of 15
  • 3indicating an association between two entities, typically one of belonging, in which the first is the head of the phrase and the second is something associated with it: the son of a friend the government of India a photograph of the bride [with a possessive]: a former colleague of John’s
  • expressing the relationship between an author, artist, or composer and their works collectively: the plays of Shakespeare the paintings of Rembrandt
  • 4expressing the relationship between a direction and a point of reference: north of Watford
  • 5expressing the relationship between a general category or type and the thing being specified which belongs to such a category: the city of Prague the idea of a just society the population of interbreeding individuals this type of book
  • 6expressing the relationship between an abstract concept having a verb-like meaning and a noun denoting the subject of the underlying verb: the opinion of the directors the decision of the County Council
  • where the second noun denotes the object of the underlying verb: the murder of two boys payment of his debts an admirer of Dickens
  • where the head of the phrase is a predicative adjective: it was kind of you to ask I am certain of that
  • 7indicating the relationship between a verb and an indirect object:
  • with a verb expressing a mental state: I don’t know of anything that would be suitable
  • expressing a cause: he died of cancer
  • 8indicating the material or substance constituting something: the house was built of bricks walls of stone
  • 9North American expressing time in relation to the following hour: it would be just a quarter of three in New York

Phrases

be of

possess intrinsically; give rise to: this work is of great interest and value

of all

denoting the least likely or expected example: Jordan, of all people, committed a flagrant foul

of all the nerve (or British cheek)

an expression of indignation.

of an evening (or morning etc.)

informal
  • 1on most evenings (or mornings etc.).
  • 2at some time in the evenings (or mornings etc.).

Origin:

Old English, of Germanic origin; related to Dutch af and German ab, from an Indo-European root shared by Latin ab and Greek apo

It is a mistake to use of instead of have in constructions such as you should have asked (not you should of asked). For more information, see have (usage).