A polyseme is a word or phrase with different, but related
senses. Since the test for polysemy is the vague concept of the relatedness, judgments of polysemy can be difficult to make. Because applying pre-existing words to new situations is a natural process of language change, looking at words'
etymology is helpful in determining polysemy but not the only solution; as words become lost in etymology, what once was a useful distinction of meaning may no longer be so. Some apparently unrelated words share a common historical origin, however, so etymology is not an infallible test for polysemy, and dictionary writers also often defer to speakers' intuitions to judge polysemy in cases where it contradicts etymology. English has many polysemous words. For example, the verb "to get" can mean "procure" (I'll get the drinks), "become" (she got scared), "understand" (I get it) etc.
In vertical polysemy a word refers to a member of a subcategory (e.g., 'dog' for 'male dog').
 A closely related idea is
metonymy, in which a word with one original meaning is used to refer to something else connected to it.
There are several tests for polysemy, but one of them is
zeugma: if one word seems to exhibit zeugma when applied in different contexts, it is likely that the contexts bring out different polysemes of the same word. If the two senses of the same word do not seem to fit, yet seem related, then it is likely that they are polysemous. The fact that this test again depends on speakers' judgments about relatedness, however, means that this test for polysemy is not infallible, but is rather merely a helpful conceptual aid.
The difference between
homonyms and polysemes is subtle.
Lexicographers define polysemes within a single dictionary
lemma, numbering different meanings, while homonyms are treated in separate lemmata.
Semantic shift can separate a polysemous word into separate homonyms. For example,
check as in "bank check" (or Cheque), check in chess, and check meaning "verification" are considered homonyms, while they originated as a single word derived from
chess in the 14th century. Psycholinguistic experiments have shown that homonyms and polysemes are represented differently within people's mental
lexicon: while the different meanings of homonyms (which are semantically unrelated) tend to interfere or compete with each other during comprehension, this does not usually occur for the polysemes that have semantically related meanings.
 Results for this contention, however, have been mixed.
 polysemy means that, "each text is seen to generate a potentially infinite range of meanings," making, according to
 "any homology, out of the most heterogeneous materials, possible. The idea of signifying practice—texts not as communicating or expressing a pre-existing meaning but as 'positioning subjects' within a process of
semiosis—changes the whole basis of creating social meaning".
One group of polysemes are those in which a word meaning an activity, perhaps derived from a verb, acquires the meanings of those engaged in the activity, or perhaps the results of the activity, or the time or place in which the activity occurs or has occurred. Sometimes only one of those meanings is intended, depending on context, and sometimes multiple meanings are intended at the same time. Other types are derivations from one of the other meanings that leads to a verb or activity.
- The human species (i.e., man vs. other organisms)
- Males of the human species (i.e., man vs. woman)
- Adult males of the human species (i.e., man vs. boy)
This example shows the specific polysemy where the same word is used at different levels of a
taxonomy. Example 1 contains 2, and 2 contains 3.
- a small burrowing mammal
- consequently, there are several different entities called moles (see the
Mole disambiguation page). Although these refer to different things, their names derive from 1. :e.g. A
Mole burrows for information hoping to go undetected.
- However: other senses of the word -- the skin blemish, the breakwater, the unit of measure, and the Mexican sauce -- are
homonyms, not polysems, as they are each etymologically distinct.
a financial institution
- the building where a financial institution offers services
synonym for 'rely upon' (e.g. "I'm your friend, you can bank on me"). It is different, but related, as it derives from the theme of security initiated by 1.
- However: a river bank is a
homonym to 1 and 2, as they do not share etymologies. It is a completely different meaning.
 River bed, though, is polysemous with the beds on which people sleep.
- a bound collection of pages
- a text reproduced and distributed (thus, someone who has read the same text on a computer has read the same book as someone who had the actual paper volume)
- to make an action or event a matter of record (e.g. "Unable to book a hotel room, a man sneaked into a nearby private residence where police arrested him and later booked him for unlawful entry.")
- a company that publishes written news.
- a single physical item published by the company.
- the newspaper as an edited work in a specific format (e.g. "They changed the layout of the newspaper's front page").
The different meanings can be combined in a single sentence, e.g. "John used to work for the newspaper that you are reading."
- The verb milk (e.g. "he's milking it for all he can get") derives from the process of obtaining
- the material made from trees
- a geographical area with many trees
- a bird with a long neck
- a type of construction equipment which looks like it has a long neck
- to strain out one's neck