1sub·sti·tute 
/ˈsʌbstəˌtu:t, Brit ˈsʌbstəˌtju:t/ noun
plural sub·sti·tutes /ˈsʌbstəˌtu:t, Brit ˈsʌbstəˌtju:t/ noun [count] 1 : a person or thing that takes the place of someone or something else
▪ a fat/sugar/meat substitute — often + for ▪ Carob is used as a substitute for chocolate. ▪ When learning a language, there is no substitute for living among native speakers. ▪ Watching the movie is a poor substitute for reading the book. 2 sports : a player who takes the place of another player during a game
▪ Gonzales came on as a substitute [=replacement] during the second half. 3 US : substitute teacher
▪ a fat/sugar/meat substitute — often + for ▪ Carob is used as a substitute for chocolate. ▪ When learning a language, there is no substitute for living among native speakers. ▪ Watching the movie is a poor substitute for reading the book.
▪ Gonzales came on as a substitute [=replacement] during the second half.
— substitute adjective always used before a noun
▪ a substitute mother/father ▪ substitute players
▪ a substitute mother/father ▪ substitute players
