onerously

adverb onerously

• hard — not soft; solid and firm to the touch; unyielding to pressure and impenetrable or almost impenetrable.
• burdensome — If you describe something as burdensome, you mean it is worrying or hard to deal with.
• difficultly — not easily or readily done; requiring much labor, skill, or planning to be performed successfully; hard: a difficult job.
• exhaustingly — In an exhausting manner.
• heavily — with a great weight or burden: a heavily loaded wagon.