Adequately means doing something well enough to meet the basic requirements or needs, but not necessarily in an outstanding way. When you study adequately for a test, you prepare enough to pass or do reasonably well, even if you don't earn the top score. When a raincoat protects you adequately from a storm, it keeps you dry enough, though you might get a little wet.

The word sits in an interesting middle ground. If your teacher says your essay “adequately addresses the prompt,” that's not high praise, but it means you did what was asked. If a bridge is adequately constructed, it's safe to cross, though it might not win any engineering awards.

Something adequate matches what's needed. A sleeping bag adequate for summer camping might not keep you warm enough in winter. Three hours might be adequate time to finish your homework, while two hours might not be.

Notice that adequately suggests competence without excellence. When you want to say someone did something really well, you'd use words like “excellently” or “superbly.” But when you want to say they met the standard and did what needed doing, adequately fits perfectly.