Definition of arch:
(n) :
an inverted U shape; an arch-shaped arrangement of trapezoidal stones, designed to redistribute downward force outward
(v) :
to form into an arch shape
"the cat arched its back"
(adj) :
knowing, clever
"I attempted to hide my emotions, but an arch remark escaped my lips."
(prefix) :
highly placed in a hierarchy, particularly used of church officials; primary among many
"he eventually rose to the rank of archdeacon"