in·ef·fi·cient 
/ˌɪnəˈfɪʃənt/ adjective
/ˌɪnəˈfɪʃənt/ adjective [more inefficient; most inefficient] : not capable of producing desired results without wasting materials, time, or energy : not efficient
▪ an inefficient worker ▪ The delivery system was very inefficient. ▪ an inefficient use of fuel
▪ an inefficient worker ▪ The delivery system was very inefficient. ▪ an inefficient use of fuel
— in·ef·fi·cient·ly adverb
▪ The engine uses fuel inefficiently.
▪ The engine uses fuel inefficiently.
