stagnant

Definitions:

Not flowing; not running in a current or stream; motionless; impure, in consequence; dull; not brisk.
- Nuttall's Standard dictionary of the English language. By Nuttall, P.Austin. Published 1914. (adjective) (adj.) (adjective)
Not flowing; motionless; still; inactive; dull.
- Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874. (adjective) (adj.) (adjective)
Not flowing; motionless; corrupt from standing; dull.
- The Clarendon dictionary. By William Hand Browne, Samuel Stehman Haldeman. Published 1894. (adjective) (adj.) (adjective)
Stagnating: not flowing: motionless: impure from being motionless: not brisk: dull.
- The american dictionary of the english language. By Daniel Lyons. Published 1899. (adjective) (adj.) (adjective)
STAGNANTLY.
- The american dictionary of the english language. By Daniel Lyons. Published 1899. (adverb) (adv.) (adverb)
Not flowing; stale or foul from standing; not brisk or active; dull; sluggish.
- The Winston Simplified Dictionary. By William Dodge Lewis, Edgar Arthur Singer. Published 1919. (adjective) (adj.) (adjective)
Stagnancy.
- The Winston Simplified Dictionary. By William Dodge Lewis, Edgar Arthur Singer. Published 1919. (noun) (n.) (noun)

Usage examples:

Her conversion was an event that broke the lethargy of their stagnant life.
- Leila or, The Siege of Granada, Book V. by Edward Bulwer Lytton
Why not, before plunging into the stormy deep, take a dip in to-" " Stagnant water," Markelov put in.
- Virgin Soil by Ivan S. Turgenev
Stagnant and flat it had always been, but never half so dreary as now.
- A Terrible Secret by May Agnes Fleming