1re·tard 
/rɪˈtɑɚd/ verb
re·tards; re·tard·ed; re·tard·ing /rɪˈtɑɚd/ verb [+ obj] formal : to slow down the development or progress of (something)
▪ The chemical will retard the spread of fire. ▪ The problems have retarded the progress of the program.
▪ The chemical will retard the spread of fire. ▪ The problems have retarded the progress of the program.
