oscillation
/ˌɑːsəˈleɪʃən/
noun
plural -tions
the act of regularly moving from one position to another and back to the original position [noncount]
somewhat formal :a frequent change from one state, position, or amount to another [noncount]
somewhat formal :the act of changing from one belief, feeling, etc., to an opposite one - usually + between; [noncount]
[count] technical :a single movement from one position or state to another
US