• Hash symbol, #, called "number sign" or "pound sign" in the USA and Canada
• Hashish, a psychoactive drug derived from the Cannabis plant
• Hash (food), a coarse chunky mixture of beef and other things, e.g. corned beef hash; cf. Hash brown
• Hash House Harriers, a loosely-organized group of social organizations focused on running and camaraderie; also referred to as "hashing"

Hash function

• Cryptographic hash function, a hash function suitable for use in information security
• Hash table, a data structure associating keys with values using a hash function
• Associative array, an abstract data type often implemented as a hash table
• Geometric hashing, a method for efficiently finding geometric objects of the same or similar shape

Hash mark

• Hatch mark, in mathematics, sometimes called a hash mark or tick mark, a short line perpendicular to an axis in analytic geometry
• Hash marks, the markings on hockey rinks and gridiron football fields
• Service stripe, commonly called a hash mark, a decoration of the United States military