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Webster 1828 Edition

adv.

With suffering of body; with affliction, uneasiness or distress of mind.

Laboriously; with toil; with laborious effort or diligence.

painfully ‎(comparative more painfully, superlative most painfully)

In a painful manner; as if in pain.
That was the most painfully sung rendition of "Fly Me to the Moon" that I've ever heard.

in a painful manner

Italian: dolorosamente (it)
Polish: boleśnie (pl)
Russian: боле́зненно (ru) ‎(boléznenno), бо́льно (ru) ‎(bólʹno), мучи́тельно (ru) ‎(mučítelʹno)
Spanish: dolorosamente (es)