to suffer: to be on the receiving end of pain, hardship, harm, or death
In ordinary Greek this verb was one of the most colorless words in the language. It simply meant to have something happen to you, good or bad, the natural counterpart to acting on someone else. By the first century, though, common usage had already squeezed it toward the painful side, and the New Testament takes that narrowing to its limit: nearly every occurrence means "to suffer." A doctor's patient, a person being punished, someone struck by misfortune, all could be described with this one verb.
What the New Testament adds is theological focus. The single sharpest use is the plain claim that the Messiah had to suffer, a statement the early church learned to make without further explanation: when Luke writes that the Christ would suffer and then enter his glory, no one needed to ask what kind of suffering he meant. The cross had given the word a fixed reference.
From there the same verb reaches outward. The suffering of believers is repeatedly named with it, and named deliberately as a share in Christ's own suffering rather than a separate misfortune. Paul can even call suffering for Christ a gift given alongside faith. Underneath all of this still runs the plainest sense of all: a sick child suffers badly, a woman suffers under doctors who cannot help her, a person bitten by a snake suffers no harm. The senses below sort these uses, but they are one word: to be the one to whom hard things happen.