hash mark

noun
1.
Informal.
  1. a service stripe.
  2. the symbol #.
2.
Football. the marking formed by either inbounds line intersecting with one of the lines delineating yardage between the goal lines.
Origin
1905-10
British Dictionary definitions for hash mark

hash3

/hæʃ/
noun
1.
the character (#) used to precede a number
2.
this sign used in printing or writing to indicate that a space should be inserted
Slang definitions & phrases for hash mark

hash mark

noun phrase
  1. A service stripe, worn on the sleeve of a military uniform to mark each four-year period of service: the voice of a subaltern of God, hashmarks running down his arm for a thousand miles (1909+ Armed forces)
  2. An inbounds line marker used to help fix the point where the ball is put in play, and spaced one yard from the next mark (1960s+ Football)

[military sense apparently fr the number of years one has had free food from the Army]