Definition of side to side in English:
side to side
adverb ˌsʌɪ(d) tə ˈsʌɪd
1Close together and facing in the same direction; with the sides touching or close together.
2From one side to the other; alternately left and right from a central point.
adjective ˌsʌɪ(d) tə ˈsʌɪd
Designating movement from one side to the other; characterized by such movement.
Origin
Late Middle English. From side + to + side.
Definition of side to side in US English:
side to side
adverbˌsʌɪ(d) tə ˈsʌɪd
1Close together and facing in the same direction; with the sides touching or close together.
2From one side to the other; alternately left and right from a central point.
adjectiveˌsʌɪ(d) tə ˈsʌɪd
Designating movement from one side to the other; characterized by such movement.
Origin
Late Middle English. From side + to + side.