2
general::
Phrase(s): *dry as dust [and] *dry as a bone
1. Cliché very dry. (*Also: as ~.) • The bread is as dry as dust. • When the leaves are dry as a bone, they break into powder easily. 2. Cliché very dull; very boring. (*Also: as ~.) • This book is as dry as dust. I am going to stop reading it. • Her lecture was dry as dust—just like her subject.
McGrawhill's American Idioms And Phrasal Verbs