punctum

noun
  1. A small dot, point, or mark; a tiny spot or puncture.
  2. Usage: Latin origin; used in English primarily in technical, medical, or academic contexts
  3. In anatomy, a small opening or aperture, especially the opening of a tear duct in the eyelid.
  4. Usage: medical/anatomical term
  5. In semiotics and media theory, the element of a photograph or image that pierces or wounds the viewer emotionally.
  6. Usage: academic/theoretical term; from Roland Barthes' concept

Examples