moil

verbs

work hard

"She was digging away at her math homework"; "Lexicographers drudge all day long"

dig, drudge, fag, grind, labor, labour, moil, toil, travail

be agitated

"the sea was churning in the storm"

boil, churn, moil, roil

moisten or soil

"Her tears moiled the letter"

moil

is a type of (narrower)

stain by smearing or daubing with a dirty substance