Computing

1. Bar (computer science), a placeholder
2. Base Address Register in PCI
3. Bar, a mobile phone form factor
4. Bar, a type of graphical control element

Science and technology

1. Bar (river morphology), a deposit of sediment
2. Bar (tropical cyclone), a layer of cloud
3. Bar (unit), a unit of pressure
4. BAR domain, a protein domain
5. Bar stock, of metal
6. Sandbar

Food and drink

1. Bar (establishment), selling alcoholic beverages
2. Candy bar
3. Chocolate bar

Law

1. Bar (law), the legal profession
2. Bar association
3. Bar examination

Language

1. Bar (diacritic), a line through a letter
2. Bavarian language (ISO 639-3: bar)
3. Vertical bar, a punctuation symbol
4. X-bar theory, in linguistics

Devices

• Birch rod, made out of twigs from birch or other trees for corporal punishment
• Ceremonial rod, used to indicate a position of authority
• Connecting rod, main, coupling, or side rod, in a reciprocating engine
• Control rod, used to control the rate of fission in a nuclear reactor
• Divining rod, two rods believed by some to find water in a practice known as dowsing
• Fishing rod, a tool used to catch fish, like a long pole with a hook on the end
• Lightning rod, a conductor on top of a building to protect the building in the event of lightning by taking the charge harmlessly to earth
• Measuring rod, a kind of ruler
• Switch (corporal punishment), a piece of wood as used as a staff or for corporal punishment, or a bundle of such switches
• Truss rod, a steel part inside a guitar neck used for its tension adjustment

Science and technology

• Cuisenaire rods, to teach children arithmetics
• Rod-shaped bacterium, a shape of bacteria such as E. coli
• Rod (optical phenomenon), a photographic artifact claimed by some to be alien life
• Rod (unit), an Imperial unit of length, also known as the pole or perch
• Rod cell, a cell found in the retina that is sensitive to light/dark (black/white)
• Real-time outbreak and disease surveillance (RODS)
• rod, ISO 639-3 code for the Rogo language of Nigeria
• Rate of descent (RoD), a measurement in aviation.

Objects

• Pipe (fluid conveyance), a hollow cylinder following certain dimension rules
• Piping, the use of pipes in industry
• Smoking pipe
• Tobacco pipe
• Half-pipe and quarter pipe, semi-circular ramps for performing skateboarding/snowboarding tricks
• Piping (sewing), tubular ornamental fabric sewn around the edge of a garment.

Music

• Pipe (instrument), a traditional perforated wind instrument
• Bagpipe, a class of musical instrument, aerophones using enclosed reeds
• Pipes and drums or pipe bands, composed of musicians who play the Scottish and Irish bagpipes
• Organ pipe, one of the tuned resonators that produces the main sound of a pipe organ
• Pan pipes, see Pan flute, an ancient musical instrument based on the principle of the stopped pipe
• Piped music, or elevator music, a type of background music

Computing

• Pipeline (Unix)
• Anonymous pipe and named pipe, a one-way communication channel used for inter-process communication
• “PHY Interface for PCI Express” (PIPE), the name of a specification for the PCI Express physical layer
• Yahoo! Pipes
• sspipes.scr, a screensaver for Microsoft Windows
• PIPE Networks, an Australian company primarily involved in setting up peering exchanges

Technology

• Pipe (casting), a type of metal-casting defect
• Boatswain's pipe, an instrument used for signalling or to issue commands on a warship
• PIPES, a common buffer used in chemistry and biology laboratory work
• Pipe (car), a Belgian automobile manufacturer

Other uses

• Pipe (letter), the IPA letter for a dental click
• Pipe (unit) or butt, a cask measurement for wine barrels
• Volcanic pipe, a deep, narrow cone of solidified magma

Pole

• Staff, a weapon used in stick-fighting
• Quarterstaff, a European pole weapon
• Staff of office, a pole that indicates a position
• Staff (railway signalling), a token authorizing a locomotive driver to use a particular stretch of single track
• Level staff, also called levelling rod, a graduated rod for comparing heights
• Fire staff, a staff of wood or metal and Kevlar, used for fire dancing and performance
• Flagstaff, on which a flag is flown
• Scout staff, a tall pole traditionally used by Boy Scouts, which has a number of uses in an emergency
• Pilgrim's staff, a walking stick used by pilgrims during their pilgrimages.

Mathematics

• Branch, in graph theory, a path is a sequence of edges connecting nodes in a graph or tree
• Branch, in set theory, a maximal chain in a tree.

• Branch (academia), an academic sub-discipline
• Branch (bridle), a crooked piece of iron in a bit shank
• Branch (computer science), a point in a computer program where program-flow may change depending on a condition
• Branch (hieroglyph), a member of the trees and plants hieroglyphs

Thin elongated objects

• Twig
• The weapon used in stick fighting
• Walking stick, a device to facilitate balancing while walking
• Shepherd's crook
• Swagger stick
• Digging stick
• Swizzle stick, used to stir drinks

Sports

• Bandy stick, used in bandy
• Cue stick, used in pool, snooker and carom billiards
• Hockey stick, used in hockey
• Field hockey stick
• Ice hockey stick
• Lacrosse stick, used in lacrosse

Music

• Drum stick, used to strike drums
• Part of a bow used to play a string instrument
• Chapman Stick, an electric musical instrument in the guitar family
• Percussion stick, a struck percussion instrument.

Transportation

• Stick or stick shift, an automobile's manual transmission
• Gear stick, used in a manual transmission-equipped automobile to change gears
• Control or centre stick, an aircraft cockpit arrangement

Food

• Pretzel sticks, pub snacks
• Breadstick, dry baked bread
• Fish sticks, processed food
• Crab stick, seafood
• Mozzarella sticks, hors d'oeuvre
• Musk stick, confection
• Cinnamon sticks, spice

Plant structures

• Plant stem, a plant's aboveground axis, made of vascular tissue, off which leaves and flowers hang
• Stipe (botany), a stalk to support some other structure
• Stipe (mycology), the stem of a mushroom under the cap
• Stem (vine), part of a grapevine
• Trunk (botany), the woody stem of a tree

Education

• Science, technology, engineering, and mathematics (STEM), a broad term used in curricula and policy
• STEM.org, an educational publisher and service
• Stem, a multiple choice question lede (excluding the options)

Language and writing

• Word stem, the part of a word common to all its inflected variants
• Stemming, a process in natural language processing
• Stem (typography), the main vertical stroke of a letter
• Stem (music), a part of a written musical note

Man-made objects

• Stem (ship), the upright member mounted on the forward end of a vessel's keel, to which the strakes are attached
• Stem (bicycle part), connects the handlebars to the steer tube of a bicycle fork
• Stem (glass), the stem of a drinking glass
• Stem, part of a watch
• Crack stem, a device for smoking crack cocain

Music and audio

• Stem (audio), a collection of audio sources mixed together to be dealt with downstream as one unit
• Stem (music), a part of a written musical note
• Stem mixing and mastering, a method of mixing audio material
• The Stems, an Australian garage rock/power pop group from the 1980s

Science and technology

• See also: § Plant structures, and § Music and audio
• Stem cell, an undifferentiated biological cell that can differentiate into specialized cells
• Stem group, of a clade (in biological classification), consists of extinct organisms more closely related to the crown group than to any other extant clade
• Science, technology, engineering, and mathematics, a grouping of academic disciplines capitalized as STEM
• Scanning transmission electron microscopy, a type of microscopy
• Spatiotemporal Epidemiological Modeler, software developed by IBM
• Stem, part of a compound variable in the Rexx computer programming language
• Main stem of a river