recess (n.)

mid-15c., ajournement, "act of postponing or deferring (a court, assembly, etc.)," from Old French ajornement "daybreak, dawn; summons (to appear in court)," from ajorner (see adjourn), with unetymological -d- added in English on the mistaken expectation of a Latin origin.

Adjournment is the act by which an assembly suspends its session in virtue of authority inherent in itself; it may be also the time or interval of such suspension. A recess is a customary suspension of business, as during the period of certain recognized or legal holidays .... Recess is also popularly used for a brief suspension of business for any reason: as, it was agreed that there be a recess of ten minutes. [Century Dictionary]

also cess-pool, "cistern or well to receive sediment or filth," 1670s, the first element perhaps an alteration of cistern, or perhaps a shortened form of recess [Klein]; or the whole may be an alteration of suspiral (c. 1400), "drainpipe," from Old French sospiral "a vent, air hole," from sospirer "breathe," from Latin suspirare "breathe deep" [Barnhart]. Meaning extended to "tank at the end of the pipe," which would account for a possible folk-etymology change in final syllable.

Other possible etymologies: Italian cesso "privy" [OED], from Latin secessus "place of retirement" (in Late Latin "privy, drain"); dialectal suspool, from suss, soss "puddle;" or cess "a bog on the banks of a tidal river."