deputy:
(plural: ‘deputies‘; for the right pronunciation, please click here)
‘Deputy’ is more commonly used in combination with other relevant words, e.g. Deputy Sheriff, Deputy Minister, Deputy Chairman, Deputy Speaker, Deputy Clark, Deputy Director, etc.

Deputy Prime Minister, Mr Naidu (L), Prime Minister, Mr Modi (M), President, Mr Kovind, of India, 2018
an assistant or junior officer who has the power to represent or work for a superior officer;
a person who assists in and/or shares the work or responsibility of another important person;
(in American English) a person who has been appointed to help a police officer (sheriff) in keeping law and order or in catching criminals;
(in some countries) an elected representative of people in a legislative (law-making) body,
The Commissioner sent his deputy to deal with the murder case. (i.e. deputy commissioner)
Our Prime Minister has sent her deputy to the UN conference. (i.e. deputy Prime Minister)
The sheriff and his four deputies have been chasing the outlaws for days. (i.e. deputy sheriffs)
