These words refer to the inward feeling or active expression of unhappiness at a bereavement, failure or loss. Grieve ahs the widest range of expressiveness, concentrating on though or feeling. It implies inner anguish that may or may not be openly expressed: giving no sign that he had spent the morning grieving over his failure to win promotion; surprised at how many attended the funeral to grieve over the death of their friend. Mourn is similar to grieve but is more formal. In its most solemn sense, it implies deep emotion felt over a period of time: privately mourning his mother’s death. But the word is often used for a public show of bereavement that may or may not be sincere but is often ceremonial or ritualized; to wear black as a symbol of mourning .

Lament comes from the Latin word for wailing or weeping. It specifically suggests giving vocal or verbal expression to a sense of loss or bereavement: loudly lamenting the loss of his job; lamenting her husband’s tragic death with uncontrolled seizures of hysterical weeping. The word is sometimes used in a less serious sense to indicate someone who tediously verbalizes trivial disappointments: lamenting to all his friends about how unfairly the teacher had treated him. Sorrow may suggest milder feelings or a less tragic loss than the foregoing words; it combines sadness with regret, contrasting with lament by suggesting grieving that is inward or, at most, quietly expressed: sorrowing over all their missed chances to get to know each other better. In some contexts, sorrow as a verb may sound faintly outdated. Grieve contrasts with sorrow and lament in that it may apply to a forlorn animal as well as to a human being: a man sorrowing for weeks over the death of his dog; a dog grieving over the death of its master.