If you do something effortlessly, you do it in that skilful, easy-looking way. She caught the ball effortlessly; he moved through the song effortlessly. Same idea as effortless, but now it tells you about the doing, not about the thing. It is common in praise: sport, music, speech, cooking. Though actually, it can also be a little sharp. “He lied effortlessly” means the lying came too easily, and that is not a compliment. As with effortless, the tidy meaning is skill that hides the work; the loose meaning is simply “with no trouble.” Listen to the rest of the sentence to hear which one you are getting. It is an ordinary word in stories and talk, a step up from “easily” when you want to praise how smooth the action looked.