dry-as-dust

[drahy-uh z-duhst] /ˈdraɪ əzˈdʌst/
adjective
1.
dull and boring:
a dry-as-dust biography.
Also, dryasdust.
Origin
1870-75; after Dr. Dryasdust, a fictitious pedant satirized in the prefaces of Sir Walter Scott's novels
Idioms and Phrases with dry as dust

dry as dust

Dull, boring, as in This text is dry as dust; it's putting me to sleep. [ c. 1500 ]