A filament is a thread-like structure that can refer to a variety of objects, depending on the context. Here are some examples of filaments:

• Electrical filament: A thin wire in an electrical bulb that produces enough heat to give out light.
• Heater filament: A thin heating element in a vacuum tube.
• Current filament: A current restricted to a small part of the conducting medium.
• 3D printing filament: The material used to form the printed object in 3D printing. The filament is usually made from ABS (acrylonitrile butadiene styrene) or PLA (polylactic acid) .
• Microfilament: A type of filament in biology that is a structural protein of the cell. Microfilaments are also known as actin filaments.
• Protein filament: A long chain of protein subunits, such as those found in hair or muscle.
• Galaxy filament: The largest known cosmic structures in the universe.
• Solar filament: A solar prominence seen against the disc of the sun.
• Hypha: A thread-like cell in fungi and Actinobacteria.
• Fiber: Natural or manmade substances significantly longer than they are wide.
• Yarn: A continuous strand of fibers twisted together.
• Filament fiber: Fiber that comes in a continuous long length.
• Filament (magazine): A female-oriented erotica magazine.
• Filament (band): A musical group from Japan.
• Filament Games: A Wisconsin-based educational video game developer.
• Filament Productions: A production design and touring video company.

The word "filament" comes from the Latin word "filum," meaning "thread".