'Bitterness' in the Bible

O daughter of my people, gird yourself [with] sackcloth, and roll about in the ashes in mourning, a mourning ceremony [as for] an only child. Make for yourself wailing of bitterness, for suddenly the destroyer will come upon us.

Thus says Yahweh, "A voice [is] heard in Ramah, lamentation, [the] weeping of bitterness. Rachel [is] weeping for her children; she refuses to be comforted because of her children, for they are no [more]."