Lensboard, lens board means just the board which covers the front of a folding camera. This board has a hole in the middle in which the lens or a lens/shutter combination is mounted. The lens board is held upright, and held at the correct distance from the film plane, by the front standard. In large format bellows cameras, and some more advanced medium-format ones, the lensboard is dismountable, and each lens will require its own board.
Often the board is mounted between poles, adjustable in its height. More sophisticated constructions allow several other lensboard movements to allow optimization of the sharpness plane and geometry of images.
The hole in the lensboard is usually of one of several standard sizes, used by all the major shutter makers. The design of the board itself varies considerably between camera makers. Some makers used flat or near-flat boards, and owners can make their own lensboards from any suitable wood or metal. Some have flanges at the edge however (for example the Pacemaker Graphics), and these boards can be sought-after parts.