If you love someone dearly, you love them very much.
She loved her father dearly.
她深深地爱着她的父亲。
If you would dearly like to do or have something, you would very much like to do it or have it.
I would dearly love to marry.
我热切地想结婚。
pay dearly , cost dearly
If you pay dearly for doing something or if it costs you dearly, you suffer a lot as a result.
He drank too much and is paying dearly for the pleasure.
他现在正为酗酒付出沉重的代价。