Searching the MeSH Thesaurus (Subject Headings)

Click the Details Details icon icon to view the details for a subject heading. Details may include any of the following fields depending on the heading.

Field Definition Examples

Controlled term in the MeSH Thesaurus. Every subject heading has a position in the MeSH hierarchy.

  • Osteoporosis
  • Computers, Molecular
  • Eidetic Imagery

The annotation instructs indexers and searchers on how to use the heading. The annotation may include instructions on the use of qualifiers.

a rheum dis; / drug ther: consider also GOUT SUPPRESSANTS & its indentions; ARTHRITIS, GOUTY is also available

[for subject heading Gout]

Scope Note

The scope notes defines the subject heading. It may include a literature reference.

The presence of parasites (especially malarial parasites) in the blood. (Dorland, 27th ed)

[for subject heading Parasitemia]

Entry Term

Synomym for or term closely related to a subject heading in MeSH. Most subject headings are entry terms for themselves.

  • photographic memory
  • memory, photographic

[for subject heading Eidetic Imagery]

See Also:

Related subject headings. See-also terms may be used instead of or in addition to the heading to search the MeSH field in MEDLINE.

  • Fasting
  • Hunger
  • Starvation

[for subject heading Food Deprivaton]


Qualifiers (also called subheadings) provide additional meaning or context for the subject heading. Use qualifiers in conjunction with subject headings to make your search more precise.

If you click ADD next to a qualifier on the details page, both the subject heading and the qualifier will be added to the text box at the bottom of the page. You do not have to add the subject heading and the qualifier in two steps.

  • classification
  • economics
  • history

[for subject heading Health Care Reform]

Pharmacological Action

The actions and/or uses of a substance with pharmacological properties. Usually expressed in terms of a class of compounds.

Anti-Inflammatory Agents

[for subject heading Cortisone]

CAS Type 1 Name

The systematic name assigned by the Chemical Abstracts Service (CAS) in accordance with the American Chemical Society naming convention.

Pregn-4-ene-3,11,20-trione, 17,21-dihydroxy-

[for subject heading Cortisone]

Registry Number

CAS Registry Number.


[for subject heading Cortisone]

Previous Indexing

Subject headings used to represent the concept before the current subject heading was established. Most of these terms are followed by a year range, indicating the years they were used for indexing the concept. If you want to find older documents, you should add these terms to your search of the MeSH field.

  • Constriction, Pathologic
  • Lumbar Vertebrae
  • Spinal Diseases

[for subject heading Spinal Stenosis]

Entry Combination

This field points to other subject headings that should be used instead of a heading/qualifier combination.

instrumentation: Endoscopes

[The subject heading Endoscopy cannot be combined with the qualifier instrumentation. Instead, the subject heading Endoscopes should be used.]

History Note

Most history notes begins with one or more dates (expressed as YY or YYYY) unless the subject heading was in the system as a main heading (or major descriptor) in 1963 and has remained unchanged as a main heading to the present.

  • 2002
  • 94; was BACTEROIDES GINGIVALIS 1992-93
  • 2004; for CHLOROFLEXACEAE use CHLOROBI 1997-2003
Unique ID

Unique identifier for the subject heading. Every identifier begins with the letter D (for descriptor).


[for subject heading Endoscopy]