What is a more common word for "efficient"?

A more common word for efficient that most people use in everyday conversation is effective, productive, or capable, though the closest everyday synonym is probably effective or good at what you do. In casual speech people often say someone is quick, fast, organized, hardworking, or gets things done rather than saying efficient, which sounds slightly technical. For example instead of saying she is an efficient worker you might say she is productive, she gets a lot done, she is organized, or she works quickly. For machines or systems, common everyday words include economical meaning uses little fuel or money, cost-effective, or energy-saving rather than efficient. If you want a very common single word, productive is probably the most used alternative, as in a productive day, or capable, skilled, or competent for people. In everyday language, saying something works well or does the job well is more common than saying it is efficient. For instance you would say this car gets good mileage rather than this car is efficient, or this method works well rather than this method is efficient. So while efficient is not rare, simpler everyday equivalents include productive, effective, organized, quick, and economical depending on context.