Saṁyutta is the past participle of saṁyujjati meaning to bind or tie. A saṃyutta is a bundle in which discourses (suttas) are presented tied together, a poetic image used to refer to bundles of packaged discourses using their subject matter as a criterion. 
Thus, the Saṁyutta Nikāya means "collection of bundles" that are grouped by subject. However, a more accurate designation would be "Interwoven Discourses," based on their structure, development, and presentation. 
The Saṁyutta Nikāya is the most important of the four collections, or nikāyas, containing the doctrinal texts of the Gotama Buddha. The others are the Digha Nikāya, the Majjhima Nikāya, the Anguttara Nikāya. There is information of other kinds in some sections of the Sutta Nipata and the Vinaya includes accounts of Sangha living and its rules. 
Usually the information is presented in two components, one biographical and the other doctrinal. The Saṁyutta Nikāya is the more important doctrinal set, where all doctrinal topics, with all their variations, are exhaustively addressed, presenting the biographical component essential to be able to locate the teachings in their place of impartation. Thus, while the Digha and the Majjhima Nikāya are full of drama, debate and narrative, here the decorative framework is absent. The whole situation is simplified into one sentence, usually abbreviated as "In Sāvatthī, in Jeta Park," and even in the fourth book this is omitted. 
The long and tortuous road that the various texts have traveled until reaching the ones we have today is a reflection of the long, diffuse and intermittent history of Buddhism in Asia. We must remember that at the time of the Buddha the cultural advances of the Harappa civilization had been forgotten for millennia. This civilization had writing and such an advanced standardization in construction techniques that the early sites were discarded as modern. The standardized fired brick throughout the Indus Valley gave way to flimsy reed and mud constructions that, as we will see in this work, reached the construction of a meeting house of unfired bricks. And it would be another century and a half before the first scripts appeared, which gradually made writing possible. Therefore, the Buddha lived technically in prehistoric times. The transmission of knowledge was exclusively oral. 
This is important for the presentation and development of this work. The discourses obey mnemonic structures made to be remembered by large groups of bhikkhus, each of them with parts that, in turn, are shared by other bhikkhus, so that the redundancy was sufficient to overcome losses of information due to the death of certain individuals or were even able to somehow survive calamities and mortalities, until a century before the common era, they decided to pass the teachings to flimsy palm leaves in order to conjure all these risks once and for all. 
Ancient Chinese served as the first written refuge for the teachings. This language is very ancient, although its availability in India was supposedly limited. Today we have received the so-called "Chinese Agamas" which are translations of oral Sanskrit texts. The drawback is that they are fragmented, scattered and largely lost. Although they do not serve to reconstruct the teaching, their value is extraordinary to find the precise definition of technical terms, since both Chinese and Sanskrit are living languages today that have an enormous and rich etymology and comparative uses. 
The most important collection that has come down to us to the present day is the "Nikāyas Pāli". While it is the most complete, it is simultaneously the most problematic. 
Pāli was never a natural spoken language. It is an artificial language with an obscure kinship to old dialects of present-day Pakistan. The pāli was created for the exclusive purpose of containing the so-called "Pāli Canon" which is a heterogeneous accumulation of texts combining versions of the originals mixed with tales, legends and classical philosophical-religious lucubrations, which were included in order to give them "authority". 
The restoration work was made possible by five factors: 
1.      They are mystical texts, and since the mystical experience is objective, it can be recognized in the text. 
2.      The interwoven structure of the texts forces the choice of the correct word to be valid in different environments and occasions throughout the work. 
3.      The support of the Chinese Agamas. 
4.      The etymologies and uses of traditionally corresponding terms in Sanskrit. 
5.      Raw access to texts in Pāli. 
Thanks to these factors it was possible to achieve the restoration of the original meaning given by the Buddha, which remained, worse than bad, under layers of millenary crusts, as a result of the accumulation of the avatars that the texts suffered during the last twenty-five centuries. The reason for this profound misunderstanding lies in the fact that the teachings of the Buddha are mystical texts addressed to people who practice mysticism and only mystics understand them in their full extent. Just like travel books where it is the travelers who get the real benefit. 
Once the last disciples of the Buddha disappear that knowledge is extinguished and the mystical path is closed. Without jhānas there is no teaching. This was already warned by the Buddha himself, who was never interested in leaving his teaching for future generations, precisely because of this. If it has reached us until today, it was not by his will but by political decision of his mortal enemy, King Ajātasattu of Māgadha, who organizes and sponsors the First Council that was already schismatic: half of the Sangha rejected the results of the council. From then on, the texts will be orphaned of meaning and will wander through centuries, councils, kingdoms and empires, always seeking the warmth of political power like any other religion. 
But today, having recovered the mysticism and being functional again, this wonderful window opened by the Blessed One opens again for those who today see what the Buddha saw, and who today live what his noble Sangha lived. 
If, in any way, it is useful to you, you are welcome to this window to the Truth.