Definition of "which" [which]

• What particular one or ones: Which of these is yours? (pronoun)
• The one or ones previously mentioned or implied, specifically: (pronoun)
• Used as a relative pronoun in a clause that provides additional information about the antecedent: my house, which is small and old. (pronoun)
• Used as a relative pronoun preceded by that or a preposition in a clause that defines or restricts the antecedent: that which he needed; the subject on which she spoke. (pronoun)
• Used instead of that as a relative pronoun in a clause that defines or restricts the antecedent: The movie which was shown later was better. (pronoun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Last year, Mr. Pinault revealed a major strategic overhaul under which PPR will gradually exit its retail business,  which includes everything from electronics to children's clothing and which has been too dependent on the French market."
• "*Replaces top of cranium…lessee..which iz occiput adn which iz frontal?"
• "HILLARY IS PART OF THE PLAN…..which is why she is receiving more campaign contributions from defense contractors (bomb, guns, tank manufacturers, etc.) than any other candidate….even republicans….(remember Hillary was the head of her college Republican Chapter) which is why she voted to invade Iraq…..then voted to invade Iran."