'Bitter' in the Bible

and they made their lives bitter with hard service, in mortar and in brick, and in all kinds of service in the field, all their service, in which they ruthlessly made them serve.

They shall eat the flesh in that night, roasted with fire, and unleavened bread. They shall eat it with bitter herbs.

When they came to Marah, they couldn't drink from the waters of Marah, for they were bitter. Therefore its name was called Marah.