form - func
- four-port circulator
- four-port filter
- four-region diode
- four-region switch
- four-region transistor
- four-speed deck
- four-stacked array
- four-terminal field-effect transistor
- four-terminal network
- four-terminal resistor
- four-terminal thyristor
- four-throw switch
- four-to-pica
- four-track recording
- four-track tape
- four-way set associative cache
- four-way switch
- four-wire channel
- four-wire repeater
- four-wire telephony
- four-wire terminating set
- four-wire transmission
- Fourier amplitudes
- Fourier analysis
- Fourier analyzer
- Fourier coefficient
- Fourier density
- Fourier filtering
- Fourier holography
- Fourier integral
- Fourier inversion
- Fourier kernel
- Fourier optics
- Fourier phases
- Fourier processor
- Fourier series
- Fourier spectrometer
- Fourier spectroscopy
- Fourier synthesizer
- Fourier theorem
