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1650s, from French oscillation, from Latin oscillationem (nominative oscillatio), noun of action from past participle stem of oscillare "to swing," supposed to be from oscillum "little face," literally "little mouth," a mask of open-mouthed Bacchus hung up in vineyards as a charm (the sense evolution would be via the notion of "swing in the breeze"); from PIE *os- "mouth" (see oral).
oscillation os·cil·la·tion (ŏs'ə-lā'shən)
The act of oscillating.
The state of being oscillated.
A single oscillatory cycle.
A stage in inflammation in which the accumulation of white blood cells in the small vessels arrests the passage of blood, thus causing a to-and-fro movement of the blood at each cardiac contraction.