1A raised table at which distinguished guests are seated at a feast, banquet, etc. Compare "high table [adjective]". Now historical.

2Sport. The higher or highest of two or more diving boards; specifically the 10m rigid board of a diving platform used in diving competitions; diving from this board as an event in a diving competition; platform diving.

Usually in form highboard. Of, relating to, or designating diving from a high diving board.