A curved structure spanning an opening and bearing weight.

• An arch-shaped entrance or passage; an archway.
• A natural opening in rock shaped like an arch.

A curved shape like an inverted U; a segment of a curve.

• The curved part of the sole of the foot; the arch.

To bend or shape into an arch.

• To cover with one or more arches.

Mischievously playful or sly; knowingly ironic.

• Chief or principal in rank or importance.

Initialism for autoregressive conditional heteroskedasticity in econometrics.