quies-, -quiet-, -quit-

(Latin: rest, calm, silent)

disquietude (dis KWIGH i tood", dis KWIGH i tyood") (s) (noun), disquietudes (pl)
A state of worry or uneasiness: When the science teacher told her students what the homework was for tomorrow, they looked at her with great anxiety and disquietude.
Ense petit placidam sub libertate quietam.
By the sword we seek peace but peace only under liberty.

State motto of Massachusetts, USA.; suggesting that military preparedness can ensure peace.

inquietude (in KWI i tood", in KWI i tyood") (s) (noun), inquietudes (pl)
A condition of restlessness or uneasiness; being uncomfortable: After hearing about the car accident on the country road, Ann's mind was in complete inquietude because she didn't know if her daughter was involved in the crash; especially, since she hadn’t returned home from her trip at the expected time.
quiescent (adjective), more quiescent; most quiescent
1. Characterized by inactivity or repose; peacefulness and at rest: "The family was quiescent as they watched the interesting film on TV."
2. In medicine, pertaining to causing no trouble or symptoms: "The doctor told Jill that her quiescent gallstones should not be a problem; at least, not for awhile."
1. Making no noise or sound; especially, no disturbing sound.
2. Free, or comparatively free, from noise.
3. Restrained in speech, manner, etc.; saying little.
4. Free from disturbance or tumult; tranquil; peaceful.
Quieta non movere.
Not to disturb quiet things.

Better translated as "Don't disturb things that are at peace"; and by extension: "Let sleeping dogs lie."

There are those now who say, "If it isn't broken, don't try to fix it." Then there are the slang-mongers who say, "If it ain't broke, don't fix it."

quietude (s) (noun), quietudes (pl)
A situation that exists with tranquillity or peacefulness.

Cross references directly, or indirectly, involving "calm, calmness, peace, quiet": pac-, peac-; plac-; seren-.