Slip Effect
"Slip" is another term for Damage Over Time that originates from the Japanese word 「スリップ」 (surippu), the status caused by the spell Bio in older installments of the Final Fantasy series (FFIV/FFVI in particular). It has seen alternate translations across games or remakes as Sap, Seize, or Seizure.
The term "Slip Effect" has never been used officially on the FFXI or POL sites, but inexplicably gets used by veteran FFXI players much to the confusion of Porter Moogles everywhere.
No relation to Indi-Slip, the geomancy Accuracy Down effect.