As the meaning of Khatam is the seal.
so how can we use the word seal as the best.

I have already answered this question. Why are you posting it in different topics?

1. خاتم النبین as the best of the Prophets and as the prophet who has the perfect qualities of the Prophethood

When ever خاتم is used for the group of a people (مرکب اضافی کے طور پر)، then it is necessary that the person who is entitled with the term خاتم becomes best of that group .
How?

It is because; you cannot produce the impression of something over the other, until that thing has perfectly and flawlessly acquired all the characteristics of that thing in it. When it has the perfect pattern (engraving, marking, impression) of something. then and only then that thing will be able to produce the impression perfectly in other things.

Similarly when a person becomes a خاتم of some group , then he must acquire all the qualities of that group fully and perfectly .

خاتم الاولیا , will be a person who have attained the quality of the ولایت perfectly in himself, then and only then he will be able to produce this quality in the other persons , thus meaning of خاتم in the term خاتم الاولیا , necessarily requires that خاتم الاولیا is the best of the all اولیا.

خاتم المفسرین , will be that who has fully and perfectly acquired the property of the group of مفسرین. Then and only then he will be able to transmit his knowledge and makes his students to become like him.

خاتم الشعرا, will be a person who have perfected himself in making poetic verses and have attained that quality fully in himself , then and only then he will be able to produce other poets .

This suggests that when the term خاتم النبین is used, then prophet hazrat Muhammad (saw) cannot become a خاتم النبین , until he (saw) has attained all the qualities of the prophethood(نبوت) perfectly, completely and absolutely in himself (saw). And as hazrat Muhammad (saw) is the most perfect prophets and all the qualities of the prophethood in him (saw) and each quality have reached to its zenith, in the pious and glorious personality of the hazrat Muhammad (saw). That is why , hazrat Muhammad (saw) is the best and superior to all the other prophets.


Our above discussion is to show that خاتم, when used as the مضاف in مرکب اضافی, then it will definitely have the meaning of
Best of that group. That is the reason you will find so many usage of the خاتم for a group of people in the meaning of BEST.

The usage of خاتم in the meaning of the BEST is the logically outcome of the fundamental meanings of the word خاتم , that is producing the impression of something on the something else. It is not listed in the dictionary meanings of the word خاتم but it will be a necessary consequence of the usage of the خاتم when it is used as the مضاف for a group as a مرکب اضافی

Hence first associated meanings of the term khataMunabeen (خاتم النبین)are the best of the prophets

قال رسول الله صلى الله عليه وسلم فإني آخر الانبياء وإنه آخر المساجد۔
آنحضرت صلی اللہ علیہ وسلم نے فرمایا میں آخری نبی ہوں اور یہ مسجد (یعنی مسجد نبوی) آخری مسجد ہے۔
(السنن الكبرى للنسائي، باب فضل مسجد النبي صلى الله عليه وسلم والصلاة فيه)

قال رسول الله صلى الله عليه و سلم : اني عبد الله لخاتم النبيين وان آدم عليه السلام لمنجدل في طينته
آنحضرت صلی اللہ علیہ وسلم نے فرمایا: میں عبد اللہ خاتم النبیین اس وقت سے ہوں جبکہ آدم علیہ السلام اپنی پیدائش کے ابتدائی مراحل میں تھے۔
(مسند احمد بن حنبل، حديث العرباض بن سارية عن النبي صلى الله عليه و سلم)

we need to refer to the verse!

God states:
Muhammad is not the father of any of your men, but he is the Messenger of Allah and the Seal of the Prophets; and Allah has full knowledge of all things.

when God states that Muhammad is not the father of any of your men he states in a way that he will leave no offspring/progeny in this world as such ...(that is only if we leave this verse at that)...
however God does not wish to leave the enemies of Hadrat Muhammad^sa pleased, by saying that Huzoor^sa left behind no issue,

and to say that he will have no prophet after him is something contradictory...
because God says that he may not have any biological male children 'wa laakin' BUT he is the seal of all the prophets...thus by saying this he has shut the mouths of the enemies by calling him the highest of all prophets...if it meant that there will be no prophet after him then (as many have put it in this forum) what is the greatness of coming last...then this verse does not make sense

ALSO Allah the Almighty says that he may not have any male childeren to carry on his progeny but he he will have Prophets who will carry on his legacy... and such people who will be the recipients of revelations and immediate dialogue from God Almighty!

The detailed answer to your question can be seen at
rahehuda.mta.tv/index.php?option=com_kun...=4543&Itemid=107
As it is already discussed in detail I thing you should be benefited from that discussion