Preferred Terms and Non-preferred Terms
After collecting terms for your thesaurus,
you need to decide which are equivalent terms.
For purposes of indexing and searching,
a set of equivalent terms will all be treated
as though they meant the same thing
and will be represented by a single preferred term.
Spelling and Synonyms
Sometimes, equivalent terms really do mean the same thing.
So, it obviously makes sense to use a single preferred term
to represent that one meaning.
- A word may have more than one spelling;
"AESTHETICS" and "ESTHETICS".
- Two different words may have essentially the same meaning;
"AUTOMATION" and "MECHANIZATION".
Sometimes, equivalent terms mean different things in ordinary
For indexing and retrieval,
it is better to group the different meanings together.
Such equivalent terms are called
Types of quasi-synonyms
Terms with overlapping meanings
are sometimes treated as equivalent.
"GENIUSES" and "PRODIGIES"
might be treated as equivalent,
even though the two terms mean different things.
A term whose scope is included in that of another term
is sometimes treated as equivalent.
"STEEL" might be treated as equivalent to
if it is not important to distinguish items on steel
from items on other metals.
Sometimes opposites are treated as equivalent,
because items on one are likely to be relevant to a query for
"TRANSPARENCY" might be treated
as equivalent to "OPACITY".
Preferred terms serve as focal points
where all the information about a concept is collected.
Non-preferred terms are included in a thesaurus
mainly to help users find the appropriate preferred terms.
Non-preferred terms may also help
to define the scope of preferred terms.
A non-preferred term is normally linked
to a corresponding preferred term
by a USE reference.
The corresponding reference in the opposite direction
if UF ("Used For").
Here the preferred term is "SERIALS"
and the corresponding non-preferred term is
Choosing Preferred Terms
The following are some principles for choosing preferred terms,
together with examples of applying them.
("Cooking" is the more commonly used word.)
("Plastics" clearly means all plastics,
of which polyethylene is only one.)
||AMERICAN LIBRARY ASSOCIATION
("ALA" could stand for something else.)
UF TRAIN STATIONS
(In an alphabetical sequence,
"RAILWAY STATIONS" would appear near to
and other terms related to railways.)
UF MUCKRAKING MOVEMENT
(One word rather than two.)
|Plural for countable objects
(Geese are countable.)
||If you have decided to prefer the Latin names for plants,
do so consistently.
||You might prefer "PIERS & WHARVES"
to "LANDINGS", "BOAT LANDINGS",
"DOCKS", "QUAYS", or "WHARVES"
partly because that is what the
of Congress Thesaurus for Graphic Material does.
||Quiz on preferred terms
Compound USE References
Instead of a single non-preferred term,
one may sometimes instruct indexers and searchers
to use more than one preferred term in combination.
In such cases, the USE reference points to all the preferred
and the UF reference is often marked in some special way.
You are especially likely to do this
if the non-preferred term consists of more than one word.
UF+ SCHOOL CAFETERIAS
UF+ SCHOOL CAFETERIAS
On the other hand,
you may choose not to make such a term
a non-preferred term,
even if it consists of more than one word.
Making Multi-word Terms Preferred
When should you allow a multi-word as a preferred term?
A term consisting of more than one word
should typically be made a preferred term if
- combining terms is not possible
either at the indexing stage or at the searching stage
- too many terms would otherwise be required to index an item
- the resulting number of preferred terms is not too large
- indexing and searching are generally easier
using the compound term
- the term is likely to be used frequently in indexing or
- the term's components occur frequently in different
"LIBRARY SCHOOLS", "SCHOOL LIBRARIES".
- the term is needed in the structure of semantic relations;
especially, if any narrower concepts are represented by
- you are in doubt
Last updated January 25, 2008, by
Copyright © 1997 The University of Western Ontario