\Four"-way`\, a.
Allowing passage in either of four directions; as, a four-way
cock, or valve. --Francis.
{Four-way cock}, a cock connected with four pipes or ports,
   and having two or more passages in the plug, by which the
   adjacent pipes or ports may be made to communicate;
   formerly used as a valve in the steam engine, and now for
   various other purposes. In the illustration, a leads to
   the upper end of a steam engine cylinder, and b to the
   lower end; c is the steam pipe, and d the exhaust pipe.