By desmond bett; B. A- criminology m. A – public administration & policy

bat: (Noun) ‘a wooden implement for hitting a ball in cricket’
b. bar (Noun) ‘a vertical line across a stave used to mark metrical accent in music’
bar (verb) ‘to obstruct’
C. fair : fair (Adjectives) ‘beautiful, attractive’
Fair (Noun) ‘holiday’
By contrast, word-forms may have the same pronunciation but different spellings and meanings. Such words are called HOMOPHONES. See this example from a joke book:
[2.12]
Why does the pony cough?
Because he’s a little hoarse.
(Young and Young 1981:57)

The joke is a pun on /h:s/, the pronunciation of the two lexemes represented in writing by horse and hoarse. Other examples of homophones include tail- tale, sail, -sale, weather- whether, see- sea-, read- reed, reel- real, seen- scene, need- kneed.

Conversely, it is also possible to have several closely related meanings that are realized by the same word-form. The name for this is POLYSEMY. Often you find several senses listed under a single heading in a dictionary. For instance, under the entry for the noun force, the OED lists over ten senses. I have reproduced the first six below:
[2.13]
1. Physical strength. Rarely in pl. (=Fr. Forces-1818.)
2. Strength, impetus, violence, or intensity of effect ME.
3. Power or mighty: esp. military power ME.b.In early use, the strength (of a defensive work etc.). Subseq, the fighting strength of a ship.1577.
4. A body of armed men, an army, in pl. the troops or soldiers composing the fighting strength if a kingdom or a commander ME .b. A body of police; often absol.the force =policemen collectively
5. Physical strength or power extended on an object; esp. violence or physical coercion. ME.
6. Mental or physical strength. Now only, power of effective action, or of overcoming resistance. ME.
The line that separates polysemy from homonymy is somewhat because it is not altogether clear how far meanings need to diverge before we should treat words representing them as belonging to distinct lexemes. In [2.13], it is not entirely clear that the sixth sense of the noun force is not sufficiently removed from the other meanings to merit an entry of its own. The other meanings all show a reasonably strong family resemblance. But mental or moral strength shows a somewhat weaker relationship.
In the OED, there is a separate entry for the lexeme force, the verb. It is considered lexeme because it has a different meaning and belong to a different word-class is an important consideration in determining whether separate dictionary entries are needed.
In real-life communication, the lack of a one-to-one match between lexemes and word-forms does not necessarily cause ambiguity. In context, the relevant meaning is normally easy to determine. But there are cases where it is not. For instance, the homonymy of bat in [2.14] can cause semantic confusion:
[2.14]
I saw a bat under the tree.

It could be a bat with which you play cricket or a small, flying mammal. This is a case of LEXICAL AMBIGUITY. We have in this sentence a word-form that represents more than one lexeme with a meaning that is quite plausible. It is not possible to determine the right interpretation of the sentence without looking at the wider context in which it appears.

We have established that the relationship between a word-form and the meaning that it represents is a complex one. This is exploited not only in literature and the word-play as we saw above but also in the language of advertising. For instance, a recent British Gas newspaper for gas heating said:
[2.15]
You will warm to our credit. It’s free.
This advertisement exploits the lexical ambiguity that is due to the fact that a warm (to) can mean ‘become enthusiastic’ or ‘experience a rise in temperature’. Next look at an advertisement, see whether it exploits any of the relationships between lexemes and word-forms that we have examined.