buy vs purchase

buy

verb
  • To obtain (something) in exchange for money or goods. 

  • To make a purchase or purchases, to treat (for a drink, meal or gift) 

  • To make a bluff, usually a large one. 

  • To bribe. 

  • To be equivalent to in value. 

  • To obtain, especially by some sacrifice. 

  • to accept as true; to believe 

noun
  • Something which is bought; a purchase. 

purchase

verb
  • To buy, obtain by payment of a price in money or its equivalent. 

  • To apply to (anything) a device for obtaining a mechanical advantage; to get a purchase upon, or apply a purchase to; to raise or move by mechanical means. 

  • To pursue and obtain; to acquire by seeking; to gain, obtain, or acquire. 

  • To constitute the buying power for a purchase, have a trading value. 

  • To obtain by any outlay, as of labor, danger, or sacrifice, etc. 

  • To put forth effort to obtain anything; to strive; to exert oneself. 

  • To expiate by a fine or forfeit. 

noun
  • A price paid for a house or estate, etc. equal to the amount of the rent or income during the stated number of years. 

  • The apparatus, tackle or device by which such mechanical advantage is gained and in nautical terminology the ratio of such a device, like a pulley, or block and tackle. 

  • The amount of hold one has from an individual foothold or ledge. 

  • Any mechanical hold or advantage, applied to the raising or removing of heavy bodies, as by a lever, a tackle or capstan. 

  • That which is obtained for a price in money or its equivalent. 

  • The acquisition of title to, or property in, anything for a price; buying for money or its equivalent. 

  • That which is obtained, got or acquired, in any manner, honestly or dishonestly; property; possession; acquisition. 

How often have the words buy and purchase occurred in a corpus of books? (source: Google Ngram Viewer )