from
The Collaborative International Dictionary of English v.0.48
ground \ground\,
imp. & p. p. of {Grind}.
[1913 Webster]
{ground cock}, a cock, the plug of which is ground into its
seat, as distinguished from a compression cock. --Knight.
{Ground glass}, glass the transparency of which has been
destroyed by having its surface roughened by grinding.
{Ground joint}, a close joint made by grinding together two
pieces, as of metal with emery and oil, or of glass with
fine sand and water.
[1913 Webster]