Isn't it confusing (and maddening) for people learning English to discover that a word can have many different meanings ? These words are called "polysemic", and they are quite common in the English language.

The word "fine" has 14 definitions as an adjective, 6 as a noun, and 2 as an adverb.  In the Oxford English Dictionary, it takes 5,000 words to describe its various meanings.  A few examples are : fine art, fine gold, a fine edge, feeling fine, fine hair, and a parking fine - all mean quite separate things.
However, the polysemic champion is the monosyllabic, modest little word which is "set".  It has 58 uses as a noun, 126 as a verb, and 10 as a participial adjective.  There are so many different meanings that it takes 60,000 words (the length of a short novel) in the Oxford English Dictionary to describe them all.

Some words owe their existance to accidents, sometimes due to a mishearing.  "Sweetheart" was originally "sweetard" (as in XIV and XV century words such as "dullard" or "dotard" - in French we still use "fêtard" and "trouillard").

Asparagus , for 200 years, was called "sparrow grass".

Penthouse was originally a "pentice" (a subsidiary structure attached to the wall of a main building)

Shamefaced used to be "shamefast" ("fast" having the same meaning here as in "stuck fast" i.e. firmly lodged.)
 

How about the words which just seemed to appear out of nowhere ?

DOG - for centuries the word was "hound" or "hund" and then in the Middle Ages the word "dog appeared, a word etymologically unrelated to any other known word.  Other examples are : jaw, bad, jam, big, gloat, fun, crease, pour, put, numskull ...

There's a certain category of words which change by becoming more specific.

"Starve" used to mean "to die" before taking the particular meaning of dying by hunger.

A "deer" was once any animal (this meaning is maintained in German with the word "tier").

"Meat" was originally any food (it can still be found in the words "sweetmeat" and "mincemeat" in which there is no meat at all)
 
 

The ending "-ese" refers to a language or place of origin: Japanese, Burmese, Maltese, Vietnamese.
It also refers to a distinctive style of language: commercialese, journalese, officialese.  In this sense it is usually pejorative in tone.
 
 

Voici un extrait de la lettre de Michael Quinion (World Wide Words) qui partage sa passion pour les mots - allez voir sa page personelle: http://www.clever.net/quinion/words/personal.htm

Dans la section "Weird Words":

Tawdry:  Something showy but cheap and of poor quality.
 

To find the source of this word we must travel to Ely, a city whose cathedral dominates the flat fen landscape of East Anglia. Long before the cathedral was built, a small religious house had been established there in the seventh century by Ethelreda, the daughter of King Anna of East Anglia. She died in 679. Sixty years later the Venerable Bede wrote that her death had been caused by a growth in her throat, which she had said was a punishment for wearing necklaces in her youth. She eventually became the patron saint of Ely, under the Norman French name of St Audrey, and her feast day, 17 October, was celebrated by a fair. One of the favourite items sold was a band of fine silk lace or ribbon worn about the neck in memory of the city's patron saint. This became known as 'St Audrey's lace', but by the end of the sixteenth century it had been corrupted to 'tawdry lace'. Eventually the first word was taken to be a description; by the nature of goods sold at fairs they often looked good until the buyer got them home, so the word became attached to such cheap and showy items, and not just at Ely.

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Haplology: Omission of one of a pair of sounds or syllables.
 

If you've ever said 'libry' instead of 'library', or 'Febry'
instead of 'February', then you have perpetrated 'haplology'. The
word was invented by the American philologist Maurice Bloomfield at
the end of the nineteenth century. He derived it from the Greek
'haplos', one or single, and '-logy', a word or speech. It's very
common in English speech to drop the second of a pair of repeated
sounds like this. A nice irony is that 'haplology' is just the sort
of word to which 'haplology' happens ...

It's a special case of what's called syncopation, a grammatical
term for losing any kind of sound in the middle of a word, such as
the poetic shortening of 'even' to 'e'en', or the way 'pacifist'
has been created from the longer 'pacificist' that was its original
spelling. In writing, the equivalent is the rarer 'haplography' -
making the mistake of writing 'philogy' instead of 'philology' for
example.
 
 

By kind curtesy of  Michael B Quinion of WORLD WIDE WORDS  fame.
Bookmark the link at the end of this extract)
 
 

Q. What is the origin of the phrase 'tall tale' (meaning a humorous lie)? What is 'tall' about it? [Douglas Maurer, Washington, DC]

A. 'Tall' is one of those curious words, like 'nice', that has had more meanings down the centuries than you can shake a stick at.
Back in Anglo-Saxon times it meant swift or prompt, and later on it variously had senses of fine, handsome, bold, strong, brave, skilful and a good fighter. It was only in the sixteenth century that it started to mean somebody or something physically higher than normal. (Even now, we can speak of somebody being 'five feet tall', in which 'tall' means having a specified height, not being of more than average height.)

Sometime in the seventeenth century, 'tall' started to mean something grandiloquent or high-flown, an obvious enough extension from the - by then - usual meaning. A little later, certainly by the 1840s, Americans had started to use it for something that was exaggerated or highly coloured, as in phrases like 'tall stories' or 'tall writing'. It's closely connected with 'tall order', something that is thought to be hard to achieve, and there were other phrases as well, such as 'tall time', meaning a long time, which Charles Dickens used.

"Tall tale" obviously belongs in among these. I haven't been able to track down its earliest recorded use (for some reason, the _Oxford English Dictionary_ has nothing earlier than 1933) but I did find this, from a lesser-known work by Jerome K Jerome of 1893 called  _Novel Notes_ : "I've come across monkeys as could give points to one or two lubbers I've sailed under; and elephants is pretty spry, if you can believe all that's told of 'em. I've heard some tall tales about elephants". I've also found this slightly earlier American one from the wonderfully titled "Gentle Hortense; or, the Maiden's Leap" by Emma E Specht: "Edward came in soon after, telling tall tales of the gentilhomme, who had been so kind to him".
 

http://www.worldwidewords.org