旺盛 （オウセイ） lively, vigorous, energetic, healthy, avid (e.g. desire), rich (e.g. imagination), full of (energy, appetite, curiosity, etc.), brimming with

旺然 （オウゼン） prosperous

盛ん （さかん） prosperous, flourishing, thriving, successful, popular, widespread, active, lively, energetic, vigorous, brisk, strong, enthusiastic, eager, hearty, frequent, repeated