The word lament can be a noun or a verb. As a noun, it means a passionate look of sadness, grief or regret. As a verb, it means mourning or expressing a deep sorrow, distress or disappointment over something.

Synonyms are bewail, deplore, grive or bemoan.

The word origins from back-formation from lamentationor or from Old French (14th century) lamenter meaning “to moan, bewail” and directly from Latin lamentari “to wail, moan, weep, lament,” and from lamentum meaning “a wailing, moaning, weeping”. It was first used as a verb in the 15th century and as a noun in 1591.

Sarah lamented over the death of her grandmother.

Lament was noticeable on her face when she found out that her cat was missing.

It hurt him so bad that he was emotionless for three days and only started to lament now.