Børsum may refer to:

• Bente Børsum (born 1934), Norwegian actress
• Lise Børsum (1908–1985), Norwegian resistance member during World War II

• Four Horsemen of the Infocalypse
• Four Hour Emergency Target
• Four Hours to Kill
• Four Hours to Kill!
• Four-Hour Work Week
• Four Houston Center
• Four Hymns for Tenor, Viola and Strings
• Fourier amplitude sensitivity testing
• Fourier Amplitude Sensitivity Testing
• Fourier-Bessel series
• Fourier component
• Fourier-Deligne transform
• Fourier (disambiguation)
• Fourier division
• Fourier domain mode locking
• Fourier integral theorem
• Fourier Island
• Fourierists
• Fourier-Laplace transform
• Fourier Motzkin elimination
• Fourier-Mukai transform
• Fourier multiplier
• Fourier multiplier operator
• Fourier Number
• Fourier-related transform