1) Audience 2) Floating library 
• (n.) The office of reader.
(1) The total number of readers of a publication (includes Primary and Pass-along readers). (2) The percentage of people that can recall a particular advertisement, aided or unaided.
Read'er·ship noun The office of reader. Lyell. 
Number of people who read a publication as opposed to the number of people who receive it.
[n] - the audience reached by written communications (books or magazines or newspapers etc.)
The number of times a publication is shared with other people is known as readership. One person might buy the Economist or Grazia but a number of people will read it. (See also Circulation, Impressions/Impacts and OTS.)
noun the audience reached by written communications (books or magazines or newspapers etc.)