Why the lord is called as Madhu Sudana

Jai Jai Manamohana Jai Jai Jai Madhusoodana

Maadhava, Keshava, Keshava Maadhava

Jai Gopaala Gopaalana (Hari)

Why the lord is called as Madhu Sudana?

Arjuna calls Krsna Madhusudha multiple times in the Bhagavad gita (1.35, 2.1, 2.4, 6.33, and 8.2). 

एतान्न हन्तुमिच्छामि घ्नतोऽपि मधुसूदन |

अपि त्रैलोक्यराज्यस्य हेतो: किं नु महीकृते || 35||

etān na hantum ichchhāmi

ghnato ’pi madhusūdana

api trailokya-rājyasya heto ḥ

kiṁ nu mahī-kṛite

O Madhusudan, I do not wish to slay them, even if they attack me. If we kill the sons of Dhritarasthra, O Janardan, what satisfaction will we derive from the dominion over the three worlds, what to speak of this Earth?

सञ्जय उवाच |

तं तथा कृपयाविष्टमश्रुपूर्णाकुलेक्षणम् |

विषीदन्तमिदं वाक्यमुवाच मधुसूदन: || 1||

sañjaya uvācha taṁ tathā kṛipayāviṣhṭamaśhru pūrṇākulekṣhaṇam

viṣhīdantamidaṁ vākyam uvācha madhusūdanaḥ

Translation

Sanjay said: Seeing Arjun overwhelmed with pity, his mind grief-stricken, and his eyes full of tears, Shree Krishna spoke the following words.

The Lord Narayan defeated this Rakshas Madhu hence he was called as MadhuSudana

Understand Madhusudana can also mean - He who defeats madhu.

 

Madhu means honey,sweet, delicious , pleasant , charming , delightful.   Sudan means slayer…..

MadhusUdana is destroyer of honey, indicating a bee.

sUdana is putting in order or guiding a right, or killing or destroying.

sUdanam is destruction, the act of killing or slaying or the act of ejecting or throwing away, and sUdanam is also the act of assenting, agreeing or promising.
Now where is the connection here?

 I have read that the ego is like honey, sweet, as it makes one forget his own identity, the SELF. And it's interesting to know that madhu also has the definition of bitter or pungent.

Lord Krishna is called as Madhavas (plural of madhu) or mAdhavas are the very yAdavas (Decendants of theYadava Clan).

madhu is “sweet, delicious, pleasant, charming, delightful, bitter or pungent”.

Madhu is “the first month of the year, or the season of spring”.

madhu indicates jIvA (“life, existence, the earth, or a bow-string”).

Madhu is “anything sweet (especilly if liquid), honey, milk or anything produced from milk (as butter, ghee, etc.), the juice or nectar of flowers, any thing sweat”.

As indicated mAdhavA is “relating to spring, or vernal”, and mAdhava is “belonging or peculiar to the descendants of madhu (i.e. the yAdavas), representing kRSNa, a son or descendant of madhu, a man of the race  of  yadu (especially kRSNa himself)”.

So at first the ego is sweet and then can be bitter. Hense Madhusadana has the ability to destroy this ego with knowledge.

It is also my understanding that Lord Vishnu tangled with Madhu and Kaitabha¹ and destroyed them. Sri Vishnu as Hayagriva fought Madhu and Katabha, retrieving the Vedic scriptures .

Hense for this and other reasons Arjuna calls Krsna Madhusudana to connect Him with Sri Visnu?

Krishna as an avtar of bhagwan Vishnu, who killed demon MADHU.   Krishna is called Vasudev as an avtar of VISHNU and not due to son of Vasudeo.

Also Krishna can be called madhusudan , as master of Vedas , which contains madhuvidya and not recognizing Vedas as prayers for physical findings by karmakand etc.

The rituals and sacrifices mentioned in the karma-kanda division of the Vedic literature are to encourage gradual development of selfrealization. 

And the purpose of self-realization is clearly stated in the Fifteenth Chapter of the Bhagavad-gita (15.15): the purpose of studying the Vedas is to know Lord Krsna, the primeval cause of everything.

So, self-realization means understanding Krsna and one's eternal relationship with Him. The relationship of the living entities with Krsna is also mentioned in the Fifteenth Chapter of Bhagavad-gita

(15.7).

The living entities are parts and parcels of Krsna; therefore, revival of Krsna consciousness by the individual living entity is the highest perfectional stage of Vedic knowledge.

This is confirmed in the

Srimad-Bhagavatam (3.33.7) as follows:

aho bata sva-paco 'to gariyan

yaj-jihvagre vartate nama tubhyam

tepus tapas te juhuvuh sasnur arya

brahmanucur nama grnanti ye te

"O my Lord, a person who is chanting Your holy name, although born of a

low family like that of a candala [dog-eater] is situated on the

highest platform of self-realization. Such a person must have performed

all kinds of penances and sacrifices according to Vedic rituals and

studied the Vedic literatures many, many times after taking his bath in

all the holy places of pilgrimage. Such a person is considered to be

the best of the Aryan family."

So one must be intelligent enough to understand the purpose of the Vedas, without being attached to the rituals only, and must not desire to be elevated to the heavenly kingdoms for a better quality of sense gratification. It is not possible for the common man in this age to follow all the rules and regulations of Vedic rituals and the injunctions of the Vedanta and the Upanisads.

It requires much time, energy, knowledge and resources to execute the purposes of the Vedas. 

This is hardly possible in this age. The best purpose of Vedic culture is served, however, by chanting the holy name of the Lord.