cross as a bear

Grumpy, ill-humored, annoyed, as in Stay away from Claire; she's cross as a bear this morning. Unlike the earlier cross as two stocks, this survives even though the adjective cross for “ill-tempered” is otherwise not used much in America. It is sometimes amplified as cross as a bear with a sore head. [Early 1700s]

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.