era vs span

era

noun
  • A time period of indeterminate length, generally more than one year. 

  • A geochronologic unit of tens to hundreds of millions of years; a subdivision of an eon, and subdivided into periods. 

span

noun
  • A small space or a brief portion of time. 

  • The space of all linear combinations of something. 

  • A portion of something by length; a subsequence. 

  • The spread or extent of an arch or between its abutments, or of a beam, girder, truss, roof, bridge, or the like, between supports. 

  • The time required to execute a parallel algorithm on an infinite number of processors, i.e. the shortest distance across a directed acyclic graph representing the computation steps. 

  • wingspan of a plane or bird 

  • The length of a cable, wire, rope, chain between two consecutive supports. 

  • Any of various traditional units of length approximating this distance, especially the English handspan of 9 inches forming ⅛ fathom and equivalent to 22.86 cm. 

  • A pair of horses or other animals driven together; usually, such a pair of horses when similar in color, form, and action. 

  • A rope having its ends made fast so that a purchase can be hooked to the bight; also, a rope made fast in the center so that both ends can be used. 

  • The full width of an open hand from the end of the thumb to the end of the little finger used as an informal unit of length. 

verb
  • To extend through the distance between or across. 

  • To extend through (a time period). 

  • To measure by the span of the hand with the fingers extended, or with the fingers encompassing the object. 

  • To generate an entire space by means of linear combinations. 

  • To fetter, as a horse; to hobble. 

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