acre vs furlong

acre

noun
  • An English unit of land area (symbol: a. or ac.) originally denoting a day's ploughing for a yoke of oxen, now standardized as 4,840 square yards or 4,046.86 square meters. 

  • Any of various similar units of area in other systems. 

  • A wide expanse. 

  • An area of 10,240 square yards or 4 quarters. 

  • A large quantity. 

furlong

noun
  • Synonym of land (“the ground left unploughed between furrows; any of several portions into which a field is divided for ploughing”) 

  • Synonym of stadion (“a Greek unit of distance based on standardized footraces, equivalent to about 185.4 metres”) 

  • A unit of distance equal to one-eighth of a mile (220 yards, or 201.168 metres), now mainly used in measuring distances in farmland and horse racing. 

  • Synonym of headland (“unploughed boundary of a field”) 

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