Baryon oscillation is basically sound waves in the early Universe.
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.