arch \AHRCH\, adjective:

1. Cunning; crafty; sly.
2. Obsolete. A person who is preeminent; a chief.

noun:
1. A curved masonry construction for spanning an opening.

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Shimell, an opera singer by trade, brings an arch theatricality to his role, making Miller sit comfortably as both a pompous author and a withdrawn husband.
-- Michael Leader, "'Certified Copy' Review," DenofGeek.com, September, 2010

Janney's performance is arch and knowing, as she mocks the mother who dispenses anti-depressants to her kids like candy and eventually tells them, "I lied to you because I love you."
-- Bret Harte, "'Life During Wartime' Review," Danville Express, August, 2010

Arch originally meant "chief," as in an archangel, but took on the sense of "mischevious" in the 1660s.