The Dictionary Meaning of the Word 'Khatam-al-Nabiyyin'

It is evident that the text can bear one meaning and it is that Khatam-al-Nabiyyin stands for the Finality of Prophethood with a clear implication that the prophethood has been culminated and finalized in Muhammad (PBUH). It is not only the context that supports this interpretation but also the lexicography.

According to Arabic lexicon and the linguistic usage Khatam means to affix seal; to close, to come to an end; and to carry something to its ultimate end.

Khatama al-'Amala is equivalent to 'Faragha min al-'Almali' which means 'to get over with the task.' 'Khatama al-Ina' bears the meaning 'The vessel has been closed and sealed so that nothing can go into it, nor can its contents spill out.'

'Khatam-al-kitab' conveys the meaning 'The letter has been enclosed and sealed so that it is finally secured.'

'Khatama-'Ala-al-Qalb' means 'The heart has been sealed so that it cannot perceive anything new nor can it forswear what it has already imbibed.'

'Khitamu-Kulli-Mashrubin' implies 'the final taste that is left in the mouth when the drink is over.'

Katimatu Kulli Shaiinn 'Aqibatuhu wa Akhiratuhu means "The end in the case of everything denotes its doom and ultimate finish." Khatm-ul-Shaii Balagha Akhirahu conveys the sense, "To end a thing means to carry it to its ultimate limit."

The term Khatam-i-Qur'an is used in the similar sense and the closing verses of Qur'anic Surahs are referred to as Khawatim. Khatim-ul-Qaum Akhirhuum means "The last man in the tribe." (Refer to Lisan-ul-'Arab; Qamus and Aqrab-ul- Muwarid). [We have referred to three lexicons here, yet the elucidation of this point is not confined to these works alone. All authoritative dictionaries of the Arabic language interpret the word Khatam in the sense that we have given to it. But the deniers of the Finality of Prophethood in their endeavor to make a sneaky assault on the religion of God argue that if we refer to someone as 'Last of the Poets' or 'Last of the Legists' or 'Last of the Commentators', we do not necessarily mean that no poet, legist or commentator will come after them; rather we only mean to say that all excellence of their act has been concentrated in such men. The actual position, however, is that when we do use these exaggerated epithets for someone we do not thereby replace or remove the original meaning of the word 'Last'. It is preposterous to assume that by its metaphorical use to refer to the excellence or perfection of a man, the word 'Last' loses its original or real significance which is 'Final'. Such an assumption can only be accepted by a person who lacks elementary knowledge of the rules of grammar. There is no grammatical principle in any language by which the metaphorical meaning of a word may be taken as its real or original meaning. Besides, the metaphorical meaning in no case replaces or obliterates the real and basic meaning of the word.
When you tell an Arab 'Ja Khatam ul-Qaum', he will certainly not take it to mean that 'the perfect or the most excellent man of the tribe has come.' He will, on the other hand, take it to mean that 'the whole tribe, even to the last man, has come.'
There is another point to be considered. Such terms as the 'Last Poet', the Last Legist' or the 'Last Narrator of hadith' are eulogies used by men for other human beings whom they deem to be perfect and excellent. Those who use these hyperboles for other men certainly can not say, nor do they know, that people of such excellence will come in later times or not. So in human language these appellations are hyperboles, but when God uses for a person that such and such quality has been culminated in him, there is no reason to take it in the metaphorical sense in the strain of human expression. If Allah had pronounced someone as 'Last Poet', he would have been last poet in the literal sense of the word. If Allah appoints someone as His 'Last Prophet', there is absolutely no possibility of any other person attaining to that dignity after that.
God is Omniscient. Man has but limited knowledge. This being so, how can one construe the human praise of a person as 'Last Poet' or the last of the jurists in the same sense as God's pronouncement of a person as the 'Last Prophet'?]

For this reason all linguists and commentators agree that Khatam-ul-Nabiyyin means 'The Last in the line of Prophets.' The word Khatam in its dictionary meaning and linguistic usage does not refer to the post office stamp which is affixed on the outgoing mail. Its literal meaning is the 'seal' which is but on the envelope to secure its contents.