in tandem

1 one behind another.

2 alongside each other; together.

☞ The Latin word tandem means 'at length': it was originally used in English as a term for a carriage drawn by two horses harnessed one in front of the other. Sense 1 preserves this late 18th-century sense, but since the mid 20th century the phrase has been commonly used to mean simply 'functioning as a team'.