ICD-11 classes
21 Symptoms, signs or clinical findings, not elsewhere...
Mental or behavioural symptoms, signs or clinical findings
MB28 — Symptoms or signs related to personality features
MB28.D — Pessimism

ICD-11 MB28.D — Pessimism

An inclination to emphasize adverse aspects, conditions, and possibilities, or to expect the worst possible outcome.

The diagnosis includes nothing.

The diagnosis excludes nothing.

It has no clarifying diagnoses.