an act of cleaning out.
an opening or passage giving access to a place that requires occasional cleaning, as a soil pipe.
Origin of cleanout
1885–90, Americanism; noun use of verb phrase clean out
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for cleanout
Historical Examples of cleanout
Traps should be provided with cleanout screw openings, caps, etc., to facilitate cleaning.