Definition of arduously:
painfully (part of speech: adverb)
difficultly (part of speech: adverb)
Ever since I have resumed my work in the Holy Land I have been awaiting with eager and particular interest the detailed letters, individual as well as collective, of my loved ones in Germany, who, I am sure are arduously, devotedly and efficiently carrying on the Great Work which the Master has destined for them in this world.- "The Light of Divine Guidance (Volume 1)", Shoghi Effendi.
The people worked arduously and without intermission; the land was rich, the seasons propitious; yet they almost constantly suffered the pangs of hunger, which spread sometimes to wholesale starvation.- "Irish Race in the Past and the Present", Aug. J. Thebaud.
In the course of his long and wandering life how often had he been paid off; how often had he felt his pockets heavy with the gold so arduously toiled for; how often had he vowed to himself that this time he would keep it!- "Wild Justice: Stories of the South Seas", Lloyd Osbourne.