• Mast (botany), the edible seed and fruit produced by trees or shrubs that wildlife species will consume
• Mast cell, involved in the allergy response
• Mast (Sufism), in India, a type of religious intoxication
• Mast (film) is a 1999 Indian movie by Ram Gopal Verma
• Mast (naval), in naval tradition, a non-judicial disciplinary hearing
• Mast (sailing), a pole which holds a sail on sailing ships and boats
• Mast year, a year in which vegetation produces a significant abundance of fruit
• Radio masts and towers, poles or lattice towers which carry antennas/aerials
• Radar masts, typically on naval vessels, but also vehicles such as the 9K33 Osa.
• The primary support for a helicopter rotor
• The main vertical structure on a Forklift truck, which carries the machanism for raising and lowering the load.

Acronyms include:

• Maritime Systems and Technology Global Conference and trade-show
• Marine Science and Technology Programme of the EU
• Mega Ampere Spherical Tokamak, a nuclear fusion experiment in the UK
• Military Anti-Shock Trousers, a medical device used to counteract severe blood loss
• Marine Academy of Science and Technology, a career academy located in Sandy Hook, New Jersey
• Municipal Ambulance Services Trust, an EMS provider in Kansas City, Missouri
• Multi-Application Survivable Tether, an experimental space mission

• Michigan Alcohol Screening Test, a test for Alcoholism
• Multimission Archive at STScI, a NASA astronomical data archive
• Multi-Axial Subassemblage Testing Laboratory, an earthquake research simulation facility at the University of Minnesota, a part of NEES

People include:

• Austin Mast, botanist
• Rick Mast, former NASCAR driver