A board that attaches to (rides piggyback on) another board, such as the motherboard or an expansion card. For example, you can often add a daughtercard containing additional memory to an accelerator card.
A small circuit board that can be attached to a larger one (the motherboard), giving it new capabilities. For example, some companies manufacture daughterboards that add sampled sounds to soundcards that previously could only synthesize sounds via FM.
An integrated circuit board that attaches to another circuit board and provides additional circuitry to expand the functions of the host, which can be a MOTHERBOARD (see also) or another board, such as a video card.
A circuit board that clips onto a sound card and turns it into a GM or GS sound source. A GM daughterboard gives you 128 CD quality sounds and a GS daughterboard, over 300 sounds, everything from pianos to guitars to drums to a helicopter or shots. - Category: Manufacture of Gear
A daughterboard or daughtercard is a circuit board meant to be an extension or "daughter" of a motherboard (or 'mainboard'), or occasionally another card. In particular, daughterboards often have plugs, sockets, pins, connectors, or other attachments for other boards, which is what differentiates them from a standard expansion board such as for PCI or ISA. In addition, daughterboards usually have only internal connections within a computer or other electronic device rather than any external ones, and usually access the motherboard directly rather than through a computer bus.