If you do something showily, you do it in a big, colourful, look-at-me way. Someone may dress showily, spend showily, or decorate a room showily. The word is not always kind: it often suggests too much display, not quiet good taste. It is the adverb of showy — it tells you how something is done, not what the thing is. Though actually, people do not use showily very often when they speak. They are more likely to say in a showy way, or just call the thing showy. You will meet showily more in writing.