Meaning of TANDEM in English
tan ‧ dem /ˈtændəm/ BrE AmE noun [countable]
[ Date: 1700-1800 ; Language: Latin ; Origin: 'finally, at length' (taken to mean "lengthwise", and so used for vehicles with one horse or person in front of another) ]
1 . a bicycle built for two riders sitting one behind the other
2 . in tandem doing something together or at the same time as someone or something else:
The two companies often work in tandem.
in tandem with
The group operated in tandem with local criminals.
Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012