An inverted U shape. / An arch-shaped arrangement of trapezoidal stones, designed to redistribute downward force outward. / (architecture) An architectural element having the shape of an arch

To form into an arch shape. / To cover with an arch or arches.

knowing, clever, mischievous / principal; primary

(obsolete) chief

A principal enemy. / A supreme and most powerful enemy.

(architecture) A row of arches. / (architecture) A covered passage, usually with shops on both sides. / (video games) An establishment that runs coin-operated games.

(transitive) To cover (something) as with a series of arches.

One who shoots an arrow from a bow or a bolt from a crossbow. / (historical, obsolete) The bishop in chess.

comparative form of arch: more arch

(now rare) The Aegean Sea. / (collective) A group of islands. / (by extension) Something scattered around like an archipelago.