Theory:

Never let a thought shrivel and die
For want of a way to say it
For English is a wonderful game
And all of you can play it.
All that you do is match the words
To the brightest thoughts in your head
So that they come out clear and true
And handsomely groomed and fed—
For many of the loveliest things
Have never yet been said.
Explanation:
 
The stanza talks about the beauty of language in the world we live in. Words have more power to create or destroy as the saying goes "Pen is mightier than the sword". One can choose to use his words wisely, to give comfort and warmth to others, to encourage and bring a smile on other people's faces. The same words also have the power to discourage or ruin people's happiness. One has to make a choice and an effort to make the best use of words.
  
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Hello in different languages
 
The poet begins the poem by saying that one must never let one's thoughts to wither away and die, just because he is not sure of the right way to express it. One must not let it fade away and disappear into the darkness of confusion, thinking that there is no way to put one's thoughts into a form that others can understand. Thoughts are unique to every individual. Thoughts have the power to create great magic. But in order to create this magic, thoughts have to transform into ideas, thereby making it a contribution to the society. This is possible only if the thoughts gain a form to it.
 
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Words express thoughts
  
Thoughts gain a form through language. The poet feels that English is a wonderful language, to give form to words. English is like a game, which can be played by anyone who wants to. Every word or sentence gains meaning as a result of the rules of this game. The language is compared to a game because it is like a puzzle or a crossword, where one identifies the question or thought and connects it to the appropriate word. The poet says it is very easy to picturize one's thoughts, as all one has to do is to match the words in the language with the brightest thoughts in one's mind.
  
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The English language
 
By considering a language as a game, and matching each word with the respective thoughts, they are expressed clearly and truthfully. There is no fear of miscommunication. When thoughts are understood by other people, the goal of the person is achieved and it can further be implemented into reality. The poet calls this process of thoughts becoming action as "Handsomely groomed and fed", as he is comparing it to a person who is well clothed and fed. Such a person exhibits a special charm over the others. Similarly, words which are clearly expressed satisfies its true purpose of conveying the right meaning.
 
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Miscommunication
 
It is important that one expresses his/her thoughts clearly and precisely with the appropriate words because there are a lot of things that are unsaid and not expressed in this world. This is due to people not being able to express their views and thoughts clearly. The poet wishes that these unsaid things that hold a lot of beauty in it be made into a more beautiful idea, by giving shape to one's thoughts using the power of words in a language.
 
Meaning of difficult words:
  
SI.no 
Words
Meaning
1
ShrivelTo shrink, to become small
2
GroomedTo clean and prepare oneself
3
HandsomelySmart and attractive
4
MightierStrong and powerful
5
ComfortIn a relaxed state
6
WarmthKind and friendly
7
EncourageTo give hope and support
8
RuinDestroy or spoil
9
WitherTo become weak and disappear
10
EffortPutting the energy to finish a task
11
FadeTo disappear slowly
12
PuzzleA game that is hard or confusing
13
AppropriateSuitable for a particular situation
14
PicturizeRepresenting a thing in images
15
TransformChange
16
RespectiveBelonging separately to each things that are mentioned
17
MiscommunicationNot able to communicate the correct thoughts
18
ImplementedTo act or start using a plan
19
CharmAttract
20
PreciselyAccurately
Reference:
 National Council of Educational Research and Training (2006). Honeysuckle. The Wonderful Words - Mary O'Neill (pp.83). Published at the Publication Division by the Secretary, National Council of Educational Research and Training, Sri Aurobindo Marg, New Delhi.