stagnate
verb
[ staɡˈneɪt ]
• (of water or air) cease to flow or move; become stagnant.
Similar:
stop flowing,
become stagnant,
become trapped,
stand,
become foul,
become stale,
fester,
putrefy,
Origin:
mid 17th century: from Latin stagnat- ‘settled as a still pool’, from the verb stagnare, from stagnum ‘pool’.