22 synonyms for efficient such as cost-effective, businesslike, and coherent. Efficient is an adjective, and its antonyms are inefficient and disorganized.
Businesslike, coherent, cost-effective, effective, energy-efficient, energy-saving, fuel-efficient, labour-saving, logical, methodical, orderly, productive, streamlined, structured, systematic, systematized, well ordered, well organized, well planned, well regulated, and well run.