adj

• (hyperbolic geometry, said of a pair of lines) Either not intersecting, or coinciding.
• (computing) Involving the processing of multiple tasks at the same time.
  "a parallel algorithm"
• (figuratively) Analogous, similar, comparable.
  "the parallel lives of two citizens"
• (science fiction, of realities, dimensions, timelines, etc.) Coexisting but normally not interacting with the regular reality.
  "parallel universe"

noun

• (geography) A line of latitude.
  "The 31st parallel passes through the center of my town."
• (military) One of a series of long trenches constructed before a besieged fortress, by the besieging force, as a cover for troops supporting the attacking batteries. They are roughly parallel to the line of outer defenses of the fortress.
• (printing) A character consisting of two parallel vertical lines, used in the text to direct attention to a similarly marked note in the margin or at the foot of a page.