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FD(1) See functional dependency.
(2) (Floppy Disk) For example, FD/HD refers to a computer with a floppy disk and hard disk. See floppy disk.
(2) (1) The hexadecimal equivalent of 254 in decimal or 11111101 in binary. See hex and hex chart.
A fixture providing an opening in a floor to drain water into a plumbing system; in homes, usually fitted with a deep seal trap.