transitive. To chafe, irritate. Chiefly with regard to the mind: To annoy, distress, vex, worry. Also, to fret oneself; and to bring into or to (a…

transitive and intransitive. To wear down with fretting; to worry excessively. Also reflexive.

To disturb, disquiet, trouble; to make anxious, fill with concern. Obsolete.

reflexive. Obsolete.

transitive. Chiefly passive and reflexive. To weary, fatigue; to harass, torment, worry. Also with object complement. Now rare.

Jocularly attributed to persons, esp. in phrases, to fret one's gizzard: to worry oneself. See also to stick in the gizzard at stick, v.1 26b.

In phrases to worry (oneself), be worried, sick.