"sleeper cells" (WOTY candidate?)

[Douglas G. Wilson]

I think "sleeper cell" means simply a cell of sleepers. "Cell" meaning
"small group [of spies/subversives/etc.]" -- back in the day, it was
usually "Communist cell", and I think this type of organization was
considered characteristic of Communists -- is cited from 1925 in my OED.
"Sleeper" = "dormant spy/saboteur" is cited from 1955 in my OED, but I
think it might be older. AHD4 gives good definitions.

-- Doug Wilson