Definition of "closer"

closer¹

/ˈkləʊ.sə/

adjective
1. comparative form of close: more close
  Quotations
  In the spring of 1938 the Japanese imperialists invaded Yü-tz'u and T'ai-ku in Shansi. Everyone was in panic as the flames of war came closer and closer to Hsiang-yüan hsien.
  1976, Sidney L. Greenblatt, editor, The People of Taihang‎, White Plains, NY: International Arts and Sciences Press, page 168
  [The researchers] noticed many of their pieces of [plastic marine] debris sported surface pits around two microns across. Such pits are about the size of a bacterial cell. Closer examination showed that some of these pits did, indeed, contain bacteria, […].
  2013 July 20, “Welcome to the plastisphere”, in The Economist, volume 408, number 8845
2. Within a shorter distance.

closer²

/ˈkləʊ.zɚ/

noun
plural closers
1. Someone or something that closes.
2. Someone or something that concludes.
3. (sales) Synonym of close (“the point at the end of a sales pitch when the consumer is asked to buy”)
4. The last stone in a horizontal course, if smaller than the others; a piece of brick finishing a course.
  Quotations
  The longitudinal bond of the walls is only 24 inches, or one fourth of the length of a brick of 9 inches, and is obtained by introducing closers 24 inches broad
  1852, Notes on Building and Road-making
5. (baseball) A relief pitcher who specializes in getting the last three outs of the game. See Wikipedia:closer (baseball)